Considering this is an XBLIG release, the graphics in-game aren't as important as the preview material and I think you've made good choice on setting priorities. Video, title screen and game cover pic looks fine to me. The still screenshots aren't as good as the animation with overlaid photoshop/particle effects. Overall the style is homogen which is a highpoint but I also think there's room for improvement in the graphics department that wouldn't require too much reworking, especially color palette tweak. Toning down the bright pinks, yellow, purple and green would make the scenes more harmonious to me.