The special stages are going to have kickass music.

This is a remix of this.

Yeah, those songs are pretty awesome. Especially Ballade's.

Now, for some official artwork of the Mega Man Killers, and screenshots of their stages:
Bass makes ANY boss in this game look like a total bitch. It's awesome.
Downloading him also gives you a new title screen.
Just downloaded Special Stage 1. It's alot faster to go through if you use Rush Jet to go over the disapearing blocks. The drill tunnel section was a nice throwback though.
Enker got a massive upgrade. He's much harder than he originally was. He's super fast and hits hard.