We use it
This works well for different torso lengths, and grows with the child. It claims to be cooler than the regular version, but it's still pretty warm - I don't recommend for long periods in hot weather. Also, don't think you'll go for long hikes with this- baby's inner thighs and butt will get sore after a while with any of these type carriers. We did do shorter hikes using this from 6-9mo old. We used it for our first until she was about a year, then gave it to a friend for hers, now were using for our second-- pretty durable. Adjustment directions are on the inside of the product so you'll never lose them. It's very quick and easy to adjust. Baby LOVED going shopping in it from about 3-6 months, once she could face forward. I'm happy we bought it.

Baby gift
I purchased this for a baby gift. Parents had registered for this at a store and the price on Amazon was much better even after having to pay for expidited shipping.

Great overall product
I bought this carrier because my son likes to face out, and the carrier that we had does not support that. Also, he was born on the smaller side, and Baby Bjorn carriers are made to carry babies as small as 8 lbs, so we could use it comfortably sooner. My only complaint is that the shoulder straps are not very padded, so as the baby gets heavier it gets a little harder on your shoulders (this is why I gave it only 4 stars).

It was delivered in a timely manner and the product was new as stated.

BEST WARM WEATHER CARRIER
We used this carrier while visiting Thailand for a month in 95+ Humid days. It was so conducive to traveling and touring the city and countryside. Our little girl (4months) comfortably slept while we visited the palaces and temples; walked 4 miles each day; rode the train without limiting my mobility or overheating baby or mom. We used the our BabyBjorn instead of a stroller and were so thankful we did. BabyBjorn can go so many places that strollers can't.

It isn't bulky, it breathes well, washes easily, and baby can easily be removed while sleeping and put into a crib.

Bjorn Air/Classic vs. Synergy/Active vs. Comfort vs. Ergo
I'm a bit compulsive so we own quite a few carriers. For the purposes of this review, I'll skip slings, and stick to backpack style shoulder strap carriers. Specifically the Bjorn line and the Ergo.

Ergo: The most comfortable of the bunch! While it can get a little toasty for both you and baby on warm days, both wife and I felt that we could wear it just about forever. Unlike most backpack carriers, the Ergo has a waist belt on which most of the baby's weight rests. Those of you who've used a hiking backpack know exactly how much this helps. For those who don't, there's a padded band that sits just above your hips. When worn correctly most of the baby's weight is distributed across your hips greatly reducing the stress/load on your shoulders and back. Unfortunately for us, our little monkey recently decided that she must face out, and the Ergo only allows them to face in. So it's been sitting in unused in the closet for several weeks.

Bjorn Air/Classic: Smallest, lightest and easiest to use. We have the "Air" model, and the special fabric actually does work to keep you and your baby cool. It's my preferred carrier for quick jaunts and hot days. But the wife and nanny will wear it only if they have to. It is by far the least comfortable carrier we own. The shoulder straps are unpadded and relatively thin so they really dig into your shoulders. I find it merely a bit annoying, but the wife says she can't wear it for more than 5 or 10 minutes before it really starts to hurt.

Bjorn Synergy/Active: Basically the Air/Classic but with wider, padded shoulder straps and a lumbar support piece. While a little more comfortable than the Air/Classic, it is still a far cry from the comfort of the Ergo. While the lumbar support is okay, the fundamental problem remains: all the weight is still placed on the shoulders.

Bjorn Comfort: The newest Bjorn, and by far the most comfortable. It has very wide and nicely padded straps, and like the Ergo, the Comfort has a padded waist band! While it isn't quite as comfortable as the Ergo, it comes close. I have used it for multi-hour walks with no back or shoulder discomfort. And unlike the Ergo, baby can face in or out.
A couple minor complaints. First it is quite bulky. Given the way its constructed, its actually much bulkier than even the Ergo, so it's not the easiest thing to stuff in a bag/under the stroller. Second is that as of yet you cannot buy additional bibs. One bib is included, but given how much we use the thing it's nice to have a second (note the Bjorn bibs currently sold are NOT COMPATIBLE with the Comfort). Plus while it doesn't seem as warm as the Ergo, you and baby will be plenty sweaty on hot days.

All these carriers seem very well made, and with the sole exception of the Air, I feel will last a long, long time (while so far so good, I have some reservations about the long run durability of the fabric shoulder straps of the Air). Currently we mostly use the Comfort, but I still bust out the Air on hot days or for short jaunts and all in all we are quite happy with the carrier situation. But we still have hope that one day our little one will deign to face in so we can bust out the Ergo again.


---ERGO---
Pros: Most comfortable
Cons: Baby can only face in. A little warm on hot days.

---Bjorn Air/Classic---
Pros: Easiest to get baby into/out of. Air is fabulous for hot days. Smallest and lightest (great for packing).
Cons: Least comfortable. Some concern about durability of Air fabric.

---Bjorn Synergy/Active---
Pros: More comfortable than Air/Classic
Cons: Still no waist strap!

---Bjorn Comfort---
Pros: Comfort (almost as good as the Ergo)
Cons: A little warm on hot days. Can't purchase replacement/extra bibs. Bulkiest of all four carriers.

Wonderful product!
We purchased this product a few days before we were leaving for Colorado. We had a cheaper front carrier and my husband used it to carry our 4-month old around Target for a half-hour, and his back was sore the next day. So we knew we needed a better carrier in order to do some hiking in Colorado. The reviews for this product were great, so we decided to go with it. One day, my husband hiked over 6 miles with our daughter in Rocky Mountain National Park, and he didn't have any soreness at all the next day. He said it was very comfortable to use, and our daughter must have agreed because she even fell asleep in it! I then had to try it at the Royal Gorge, and was very impressed with how comfortable it was and how easy it was to readjust it to fit me (my husband is 6'1" and I am only 5'2"). Great product...we would recommend it to anyone who needs a comfortable way to carry their yound child!

Too Small for my infant
i'm not saying this is not a good product, but its too small for my child, this product is good for a new born till three months old.

Amazing, the instant baby soother! Can shop for HOURS!
This thing is amazing. We have this and the Moby and we ONLY use the Baby Bjorn. It is AWESOME.

Fits both me (5'11") and my husband (6'5"), and fits the baby like it was custom designed for her. She LOVES it. Sometimes it's the only thing that will calm her down when she's fussy. It's lightweight and very cool - we live in Texas and the Moby was awful in the heat - the Baby Bjorn is great!

It's SO easy to use; we leave it all attached on the left side and pop her into it and fasten it on the right side in under 4 seconds. It doesn't even wake her up. (Neither does getting her out, which is when the ability to completely unfasten it on both sides is GREAT, you can literally just detach the whole face so that she's not "in" it any longer, perfect for putting her to bed after she's gone to sleep in it).

The amazing thing is just how much she loves being in it. She slept for 2+ hours yesterday as we traipsed all through IKEA. It's nice to have her near me, she feels secure, I can keep an eye on her, and she's comfortable and happy.

Extra bonuses: you can breastfeed in it by lengthening the straps a little, which you can do while she's in it - it doesn't offer any privacy but this will be a great option if it's ever feeding time and I just need to duck into a restroom or something, no worrying about holding her or finding a sanitary spot. Also, having her attached to me means strangers aren't so likely to touch her as they are in a stroller or car seat in a shopping cart, so I'm more comfortable taking her out in public while she's still young and developing her immune system.

Wow, it's like a miracle...
We purchased the Bjorn Synergy carrier for our newborn daughter, and it has been one of the best investments in gear that we've made. She LOVES being in the Bjorn, and the head support for her as a newborn is excellent. When she's fussy, putting her in the Bjorn immediately calms her down. Sometimes she'll fall asleep, but other times she'll be bright-eyed and spend her time looking around and taking in the sights as we go about our chores.

Also, a note for tall folks. I'm 6'5" and my wife is 5'11", and we are both able to use this carrier comfortably. At first I felt I couldn't use it, even with the straps at the longest settings, because the lumbar support panel sat up way too high on my back, but then we figured out that the lumbar support will slide down along the straps, and allows for adjustments that are NOT SHOWN IN THE MANUAL. All the manual says about the lumbar support is that you should tighten the lumbar straps first, it does not describe that the lumbar support is mobile and can be adjusted up and down the straps. Once we figured this out, I was able to comfortably wear the carrier.

Another nice feature is the fabric, which is an open mesh weave. We live in Central Texas, and the heat here in the summer is oppressive, and the winters don't really get cold, and the mesh fabric allows for us and our daughter to be as comfortable as possible when we're outside. In fact, we were almost ready to purchase the Baby Bjorn Baby Air Carrier, Grey/White because of the open weave, but then we discovered that the Synergy is made from the same material, but also includes the lumbar support feature, which was very important to us.

So even though the carrier is a bit pricey, it has been worth every penny for us.

complex to put on
The original was so much easier to set up, adjust, and put on. Most of the time I get frustrated. So far, I tried putting my baby in it 10-15 times. Perhaps it will get better with practice. He does not like it yet so I don't get much practice.