Any falling block entity in 1.5 can't have another block's texture. This breaks a lot of things, like 3D animation: http://www.youtube.com/watch?v=Hl1KRMMm8y0

All of the moving blocks here would look like sand in 1.5, and it's not fun. I've included 2 screenshots, the first in 1.4.7, and the second in 1.5