The graphics, sound and music are great, it's one of the best looking games on the system for sure. The sprite animations are absolutely superb.
I'm not a big fan of the "collect the coins" gameplay, I prefer my action games to be a bit more direct and I find that collect-em-up thing distracts me from that somehow.
I also think the characters could do with somewhat more fantasy oriented names than Ryan and Julia.
That criticism aside, and the fact it's a bit on the easy side for my liking (I prefer old-school difficulty), this is shaping up to be a really good game.
I'd definitely buy a physical cart of a game of this quality.