First thing I noticed right off the bat is that this thing is 13MB. You REALLY need to cut down the music size as that's too big for just one map. I recommend that you use Audacity to loop the track and convert it into an .OGG, since it's a great music editing tool and also free. Now, on to the map itself:
- The map is extremely open, with areas that seem huge for the sake of being huge. There are a number of problems with this alone, such as the lack of proper cover and close range weapons being mostly useless (aside from Charge Kick) and a lot of flat ground that feels overall boring to run around in. What you need here is to tone down the inflated areas (a good example being the indoors area with Charge Kick), experiment with more structure that both provides cover and isn't just flat ground, and then add weapons that work well in it.
- Speaking of structure, avoid things like the long, linear paths in the outside of the map. By this I mean that, if you're making a DM map, all areas should have more than one way out of them. This prevents players from being cornered cheaply and keeps the pacing of the match flowing neatly.
- When having a variety of elevations in the map, avoid ladders going upwards a high elevation. In fact, avoid elevations that differ too greatly from the map geography unless you have provided comfortable ways for players to get around them, such as (but not limited to) jump pads and teleporters. It all depends on what works better for your map's layout.
Welp, that's all I can say here. It's nice that you got the hang of some of the basics, though.