Honestly, I'm not sensing a huge power discrepancy in the class... it just lacks anything exciting or any really "umph." It doesn't really feel like a spontaneous caster at all, even though its mechanics suggest that. What about perhaps a tweak in HD to a d6 (perhaps skill points as well), and a few flavorful abilities like "Detect Magic at will at 4th level." It doesn't have to be a whole helluva lot more powerful, but I would like to see it made more interesting.
AFAIK, this is DnD's first attempt at a spontaneous class that's also a core class. In 3.0 it was seriously lacking. 3.5 got slightly better. Hopefully they'll continue to work on it and improve it. It seems like a work in progress; hopefully wizards is reading the polls and threads over at their boards and looking at ways to improve the class, based on popular consensus and suggestions.