The shoe is slightly tight and makes your foot looks larger than it really is. Also, they are not comfortable like the ultraboost.

Decent shoes for heel strikers

These shoes are pretty decent. They have plenty of cushioning in the heel for heel strikers. I’m enjoying them for my runs.

Great response, and cushion as advertised

I really liked the Ultraboost 20s and bought 2 pairs of the Ultraboost 21 to add in my rotation. I work out 4-5 days a week, doing cardio and weights. And these feel really good on my feet. I am not an avid runner, but as advertised, the additional boost feels more responsive and more cushioned. If you liked the Ultraboost 20s, you'll like the upgrade on the Ultraboost 21s. I am a heavy set guy, I've lost over 60 lbs in the last year, and have put my Ultraboosts through the test...

Great trainer !

This is my 1st ultraboost 21, having the UB 19 before I thought I'd try these.They look great, much more futuristic looking over the ultraboost 19s.One thing I've noticed though, these are on the tight size. Maybe going up by .5 would make them as comfortable as the ultra boost 19s.

Honest review.

The fit is almost tight enough not to need any laces. I havent tried the size up. I'm normally a 8.5 on Nike but this is snug fit. The archilles tendon has two plastics to hold the shoe in and its tight if you use any cross training or side movements. Just good for running. Been running on a treadmill and not used outdoor.The top lip of my left shoe flips back and doesnt look all that great when i wear it. If only they moved the adidas label just a bit higher so it wont flip back .

I may have to get all of the colors

I purchased the 21 Boost based on previous experience with the 20's. While these are very different in looks, they provide the same comfort. I'm not a runner, but the cushion in these really help alleviate back pain during long time use. The color way is amazing, I'm a fan of the small details in the upper of the shoe with small touches of the accent color throughout. If you're looking to buy a pair but find yourself on the fence, make the jump. Your feet and back will thank you and you'll get plenty of compliments as an added bonus.

Most comfortable shoe, believe the hype

This is a very functional shoe and looks great. Got this for walking and light jogs and have to say it is thee most comfortable shoe I’ve worn. My only frame of reference are under armour running shoes and various lifestyle trainers so you don’t have to take my word for it.I went half size up, first wear was a little tight but after wearing a few times I wish I had gone true to size. That primeknit makes them so easy to break in.Very comfy and supportive, when my feet start to get tired I can sort of adjust my stepping and feels like I’m walking on clouds. Basically all parts of the shoe are comfortable so it doesn’t matter if you’re heel stepping, toe stepping, side stepping -this shoe with support you and bounce back.

Quality and style you would expect from Ultraboosts!

All out red looks exteemely sharp! The extended boost sole looks sharp and provides additional stability. Upper is well made with very little evidence of stich/glue lines. Can wear casually or for running but sole is not flat or firm enough for most gym leg-day exercises. We ordered a full size down as the shoe runs noticably large.

This model falls short (or long)

I'm a fan of ultra boost tech, have had every model and decided to buy this one on sale. When it first arrived I was super excited to try them on. Out the box, my first impression was that it seemed to follow previous models and was made from solid materials, once on foot my feelings changed. Super comfortable, light weight but LONG. Mens size 8 looked more like a 10. The silhouette was more like a clown shoe paired with a huge heel and I just couldn't keep them.