The lightsource is very strange.
On the top-left spike it seems to be coming from behind.
On the other spike it seems to be coming from the left.
On the window it looks like it's coming from directly above (with something dark to the bottom-right)
If the lightsource is indeed in the top-left, the bottom-right spike would be in shadow.
The big window looks cool, as does the right window, but the left window's hilight is pillowshaded or some other wierd thing that makes it look wierd.