The tilset is fine, its original.

The chaingun must go, it annoying and it does no fit with the rest of the map.

I think you should do what you did with the top righthand corner, ( the laser things) and put it in the bottom lefthand corner, moving the blocks that are there now (lefthand bottom corner), up a few. Having two symmetrical little laser palaces would work fine.

I feel that its hard to get into those litle crab things, (like the one on the bottom right corner) you should make the inside flat, and easier to get in and out of. You should also move the little crab pods around a little, sort of mixing up the tileset, I think it would allow the lasers to do their job more properly.

The BIG cluster of mines in the middle is sort of unnatractive, perhaps clean that up a little.

Your a little shy on gold (make it useable though)

Now remember, these are my opinions and only suggestions, you don't HAVE to do what I'm saying..

well, im done for now, (perhaps wait until others give you feedback)

I rate and comment later, cause I have to go now..