Yeah, 'tis good, but I'm not too keen on Thunderstar's colour; looks a bit like sick
Anywayz, that's just a derp-opinion from me.
Apart from that, there aren't any other "faults" but one thing I would've said about the head, is that you've drawn his forehead a bit too big, but that's not a huuuge matter.
I like how yer've coloured in the background and character, making it look shaded and shadowed.
( People seem to enjoy making the background set in a showeh environment :/ )
All in all, this is one of the "better artwork" and you may have a chance of comin' high up in the result-rankings
Well done.