It's out on Wiiware in North America, so I went ahead and downloaded it as soon as I found out.
Enjoyable stuff as usual, although I haven't finished the game yet. I can safely say Protoman isn't hell to play as anymore and is roughly about as powerful as Megaman now thanks to the lack of his previously increased knockback, and Protoman can access a shop now (albeit his shop is a bit different from Megaman's).
A new mode that's in 10 is the Challenge Mode; not like the "achievements" thing that was in 9, but a whole different set of short training courses with different goals. For instance, the very first one is a piss-easy course where you pretty much just walk to the finish, whereas others give you target practice with different robot master weapons, and others have you try to force your way through ranks of enemies.
Um, as far as I've seen, there's no actual 2 player mode. So, pull the plug on that rumor for now.
The levels are challenging like last time and have their own unique gimmicks, blah blah, ten dollars go buy this game now.
