I've messed around with Electroplankton on the mate's DS, was a
lot of fun. It's not designed to run like a DAW or anything conventional, it's all about messing around with environments to make sounds. If you sample it you could make some really unique stuff. I guess its more of a special FX approach than anything.
Seeing it uses the DS' microphone for sampling you can capture pretty much anything & a lot of its sampled sound gets a nice gritty 12bit edge.
Here's a bit of the mate (uses the pseudonym An Owl these days) messing with his voice on one of Electroplankton's modules:
Haven't used Nitrotracker, so I can't comment there. Remember he was saying it was pretty basic compared to the other trackers he's used. Pretty well suited to how you'd use a DS (switch on, get working quick, make a tune, get on with life).
Have you checked out the Korg DS-10 synth as well? It can make some great tones with a bit of work, its basically 2x MS-10s, 2x Kaoss pads (as midi controllers) & a drum synth. Its the whole reason why I bought a DS. There's an update on the program as well (DS-10+) that makes the synths polyphonic among other things, haven't used it because it was never released where I live & Nintendo region code their shit. Dumb bastards, they lost revenue with that.