Pros: great sound, comfort and great noise canceling
Honestly they are expensive, but extremely satisfying headphones. The noise cancellation works wonders, specially in planes. The headphones have a great build quality although many say they look flimsy, they are actually pretty robust and fit amazingly on the head/ears. The battery life is very good, never ran out of battery and I charge them every once in a while with daily usage of the headphones.
I never regretted buying them, they're great for moving around with them, you can walk around comfortably with them, and taking them to places isn't a hassle in any way.
If you're looking for best sound for buck and don't care about the noise cancellation, these are definitely not your choice. But if you want some great sounding headphones with great noise cancellation, and don't mind paying a little extra, then they are definitely a great choice. And specially don't let their looks deceive you, the build material isolates sound really well, combined with the noise cancellation it's amazing. You can hear your music on very low no matter where you are, even on the plane.
Clarity could be better. (they don't compare to Sennheiser)
Overall sound is great, highs and lows are good, but the mids could use a bit of work (just like most of BOSE products).
They are small in size which is amazing for what they do, and much nicer and more comfortable than most over-ear headphones.
Nevertheless, satisfying sound.
In the end it's a great product.