Hey, not bad! I can tell you've improved since you first started. Your map is functional and has some neat ideas in it, and from a color standpoint it actually doesn't look that bad either.
The problem I'm seeing right now is just a general lack of polish, mostly from a visual standpoint.
You're experimenting with scenery; that's good. Keep adding more details like this, but think about your ground and your boundaries as well; those big and imposing walls wouldn't be flat in real life, would they? They'd probably be layered with rock structures and stuff on them.
When you have a hole that leads to another area, don't just make it a hole -- dress it up with some sectors, make it less flat! Don't make your acid pits the same floor as the ground -- give them some depth.
It's more work, but small details like this go a long way.
Some other points:
* Don't abuse darkness too much. Even in a cave, it shouldn't be too hard to see what's going on.
* Don't plaster a whole bunch of red X's on high wall, looks kind of tacky because it's such a high-attention graphic. One row of X's will do and is easier on the eyes.
You should
download this circuit pack and study how they do visuals. Might help give you some ideas.