Lol, I personally hated the Block far more than the Stair pieces. Often times I'd get it and have to have part of it hanging off some other piece.
The square blocks could be useful if you formed a tower of them on the far left or far right. Any block can serve a purpose, but I found the crooked blocks to be the most annoying. They have a tendency to show up when you don't need them whatsoever. You are in desperate need of an L block, a 7 block, or an I block, then here comes a crooked block to ruin everything. Unless you have the right place to put them, they just don't fit anywhere. Plus, the T blocks can go anywhere that either of the crooked blocks can. That piece is a lifesaver in many cases.