Aw, your sis isn't that bad. The autotuning on her voice is pretty wretched, but anyway...
Disclaimer: I'm listening on some pretty mediocre computer speakers here at work with relatively low volume.
To me, the mix sounds a bit top-heavy; very bright and thin. The drums seem to occupy most of the mid range, where I'd rather hear some guitar filling out the space. The drums seem a bit up in the mix, which is not really a good thing for programmed drums (they were programmed, right? I'm not losing my ears yet?). Especially hihats.
I never really caught the bass, my speakers don't have much bass, but either you've got it buried or it's such a dark sound that my speakers aren't getting it.
Anyway, sounds clean, just needs to be meatier IMHO.