I'd also add some sort of subtle background imagery behind the bits where the player can walk.
Easily done I can add some extra graphics themes, the ZX is my current fav.
there's a lot of redundant space around the outside of the level, and it looks a bit repetitive.
If there is space on the outsides is to alow the rows to be pushed into the correct positions or to allow the player to move, Its easier to design puzzles with that way. Some of the puzzles have similar shaped rooms 3&4 do as you said but they are different puzzles, some puzzles take place in L shaped and T shaped rooms.
How did you find the 5 puzzles, the first 2 are ment to be realy easy and next two a little more advanced the fifth to realy test the player.
Its actually pretty good
How did you find the music funcky enough 4 ya?