I really like it. It's a nice mix of hard and soft materials. It's flexible, which is nice because it makes removing the case fairly easy (for those of you who want to access the phone's back cover to hot swap batteries).
For the most part, the case feels pretty smooth, which makes getting it out of the pocket an easy process (I previously used the casemate pop case and the rubber sides made it fairly annoying to pull the phone out of the pocket). The case definitely adds more grip to the phone, but overall, it still is a little bit on the slippery side. On the continuum of "slippery vs. grippy" I'd say it's a pretty good balance, but I wouldn't mind it being a little more grippy.
Even though the case is made for the international GS2, it still fits well on the AT&T SG2. The noise-cancelling mic is covered by the case, but I have not had any problems as a result of this. However, you might come into problems if you are trying to use the phone in a noisy environment. I'm a little bothered by the corner cutout for the antennae (for the international SG2) since it really leaves that corner unprotected if the phone happened to fall right on that corner. Then again, i'm just going to take my chances that i'm not going to drop my phone on that exact corner.
The case still keeps the phone very thin and sleek. Also, the case has these tiny sparkle dots that show up on the back of the case, which give off a cool effect when reflecting light. Some may say, they make the case look a little feminine, but I personally don't think they do. In all honesty, you can't even really notice them unless you look close at the case and in the right lighting.
I got the yellow ultra capsule. I've heard one person say that these cases are prone for showing up finger smudges, but at least with my yellow one, finger smudges have not been a problem.
The case covers the volume and power keys. They are still pressable and work fine, but the buttons aren't as sensitive as they are without the case. However, this difference is really negligible for me. Overall, hardware buttons work fine.
I really liked the Body Glove Mirage cases that were made for the Samsung Captivate and the Infuse. In my opinion, this case is just as good as those cases.