I can't understand why so many people rave about this. I think it looks awful, amateur-ish to the level of bad fanart.
It doesn't seem like the artists are dealing with the granularity issue. In order to make the original pixel sprites more readable, compromises were made. It's easiest to see these in the hands, fingers, and feet. When everything is scaled up, the ratios stay the same, since the artists are just drawing over it.
The second problem I have with the process -- the artists seem to be taking each frame individually rather than in context with the others. As a result, I suspect a lot of the detail they add will float around. They artists seem to be relying on a lot of extraneous lines rather than constructing solid forms like good animators would.
Then of course, there's the anatomy problems. I don't mind exaggeration or skewing, but this stuff looks plain inhuman, like mutant clones of the characters. It seems that these comic book artists learned anatomy from other comic books (paying particular attention to Rob Liefeld's work), while avoiding life drawing, figure studies, or even looking at real people.
This project would be better off if they just colorized the animated sketches for SF Alpha.