I like the twists and turns. Very rattish. And the trap(s). Also very wererat.
A few critiques:
I can tell that some of the rooms aren't exactly scaled right. The room with the pile of gold, for example, has a bigger grid than the room with the pit trap.
There aren't a lot of spaces for creatures to stand. The cramped chambers might be where wererats would actually live, but it doesn't work as a dungeon for D&D 4E. You could barely get away with rooms this small in 3E, when encounters can validly consist of 4 PCs ganging up on 1 monster. Bu in 4E, the PCs could easily encounter 8 monsters, not even using minions. Then consider the PCs themselves, and any additional monsters... there's not even room to fit them all in the room, much less have a battle, much less have a fun battle. The problem here is that you're using Dungeon Tiles, but they're not really meant to represent a room all to themselves. You need to put a couple of tiles together for it to be big enough.