I really hate alternate blocks, because it is laggy (other Pc dual core 2.5Ghz and geforce 8600 gt) and I think it looks just good on Vanilla, but most people use texturepacks (128x128) grass and the stone doesn't look good with it. The other thing is, I heard you can make texturepacks which removes alt blocks but you need to know how and look every detail up. I know many texturepack creators who said, it becomes more and more difficult to create texturepacks and alt blocks is one thing which makes it more difficult. So I hope this option will be back in future snapshot versions.