I've had a really bad acoustics issue in my computer room/mini studio.
These pieces of foam are large, and easy to cut, which made it ideal for me to use on pretty much all my walls, some on the ceiling probably wouldnt hurt either but okay, all of my issues are pretty much solved, the room sounds very dry now which is perfect for listening to music and mixing/producing using the studio monitors i've got.
In my opinion they work better than the thin wedges you can buy and are easier to mount, dependant on the room you've got you might need diffusers etc, but mines really tiny so that wasn't necessary for me.
They're easy to cut, easy to glue using the recommended glue, and they're large which is why it's easier to cover larger area's.
They also absorb really well, which got rid of pretty much all the reverberation i was stuck with.
In other words: to me a product that doesn't blow my wallet and works awesomely!