Very nice-looking acoustic treatment that is good for diffusing mid-end frequencies. Don't expect them to decrease the bass frequencies a lot -- they aren't designed for it, and for that, you'll need something more suitable like a bass trap. However, they are quite good at taking the edge off the mids and absorbing a bit of sound.
I'm using these foam pieces not in a studio, but rather in a living room. There are two pieces behind our TV and the other two pieces behind the wall where an upright piano is sitting. In both cases, the goal was to absorb a bit of sound to prevent it from leaking into the neighbor's flat (yes, I know that acoustic treatment and soundproofing are two different things, but there was other compromises to be made, which I will mention shortly). In the case of the TV, the foam noticeably decreases the amount of noise reflected off of the wall. For the piano, we put in the foam at the same time it was delivered, so I have no basis of comparison.
The other thing about this sound foam is that it looks great! My partner/wife really likes the white foam behind the TV, since it has a bit of a futuristic look. This also weighed into our choice.
One disadvantage of white foam is that it will show dust and dirt over time. You can use a dog hair roller (one of those roller stick things with the tape roll on the end) to gently remove the dust. I do this about once or twice a year and it does a good job of keeping the foam nice and clean.
