I've never been much of a midi maker but I decided to give it a crack after putting a small one up for release something. Tell me what you think.
http://www.2dadventure.com/ags/MIDIsong99.mid
Well, it has some nice features, but is pretty repetitive and has some odd parts, for example a few same notes too many in a row (especially with the main instrument they sound like the song's jammed in the same part). The main instrument doesn't work well, the sound at the beginning of each note makes them too separate (and creates the repetition I mentioned)...
But it's still got some pretty good stuff in it. Just a bit more experience...
a partial "arrange-over" (http://www.2dadventure.com/ags/REVISED.MID)
I wasn't quite sure what you were going for here, but I took a stab at re-arranging it anyway. Hope you don't mind.
The biggest thing to keep in mind here is line. The rule of thumb for creating melodic lines is that each phrase should use steps along the scale rather than jumps -- save large jumps for dramatic effect, like when the melody reaches its peak. If you can sing, try singing your lines and you'll see it's a lot easier to sing and remember a part that mostly goes step-by-step up or down the scale. When your melody is more solid, I think you'll find it clearer what to do with the other parts. I re-worked the bass line in a few places and added a really crappy harmony line, for an example ;)
I also added a different percussion track which I think helped break up the monotony of the first arrangement a bit.
Anyway, hope this helps. Lemme know if you have any questions.