I have the Isis sleeve, and the memory foam is very nice. The zipper protection is outstanding because the inner lip (also memory foam) is very high and wraps just over the top of the corners of my mbp, protecting it very well. Now the foam is not as thick as the zeroshock, but it seems sturdy (firm) in terms of elasticity. Good quality memory foam IMO.
As an aside, they have some of the best customer service ever. I had a sleeve that did not fit right at first, and took forever to zip for some reason. I was contacted by them and asked how everything was, told them about the first sleeve, and they sent me a new one free of charge without asking for the old one back (I offered and they said to keep it). I was very pleasantly surprised. The price cannot be beat either.
Great to hear...thanks for the review. I remember reading your post in the archives and it sounded like their customer service was nice which is one of the deciding factors....I figured less risk. I actually like that the foam isn't as thick as the zeroshock because I thought the zeroshock would be too thick for my tastes. Thanks again for the info!