New to the site, and it looks great. One complaint though:
I think too many problems here have many first moves which are completely winning, and it's not correct to mark it wrong if you play a completely winning move. For example, Problem 27956, 1.Rxe5 is obviously completely winning (checked with Rybka afterwards, it's +7.5, good enough for me

. In a practical game OTB with the clock ticking, if you see a completely winning move, you play it. You don't search for some obscure mate-in-5.
Similarly, in many problems here, the side to move is up lots of material, and just about any legal move wins the game. Those problems should be deleted. In a practical game it's not important to find the mathematically best move according to an engine when you are already up a piece or a rook. It's only important not to blunder. Maybe filter the problems to delete those where the side to move is up lots of material, say one piece or more.
FIDE Master Drahacik