Be careful with this.
The ipad's speakers are too small to reproduce the low-end frequencies, but a car stereo can easily give you the exact opposite problem — too much bass.
If you can, I'd recommend in investing in at least a good pair of headphones that will give you as "flat" as possible of a frequency response. I recommend the AudioTechnica ATH-M50x if you can't afford or don't have an ideal room for speaker monitors.
I re-listened to the piece after the eval and have a few criticisms I didn't notice at first. First that shrill cat-like string (I think) synth that appears often after the first minute has got to go (it clashes with the melody and has no place in a Pluto theme). I can't see any problems with 0:50 but 1:02 definitely has some harmonic clashing going on. I still like this mix but sampling Square isn't allowed sadly. Sorry if I sound harsh but it's still pretty good.
honestly I'd love to see what you could do but frantic factory was a very hectic level, gloomy galleon was *shudders* a quarter land and three quarters water... personally I like the boss music from Gloomy galleon better than frantic factory... so that's just my two cents worth
I'm liking it so far, I'm by no means a judge, or music maker by any level of measure, just my opinion, is it sounds too flat, or 2D, add some depth to really highlight the difference between intensity, and darkness, like in the intense, make it in your face without making it too loud and obnoxious, and the dark, could sound distant, eerie and spooky, but without losing too much of what your going for, otherwise, I'm really enjoying what I'm hearing, keep up the good work!