I'm a little indifferent with this...
Little Mac, I really want in. I will be pretty sad if he doesn't make it...but he's going to, so no big deal.
Miis, while I'm not openly debating about their worthiness, or anything radical like that, I do believe have earned a spot on the roster. I trust Sakurai to execute a Mii that doesn't revolve around "Play as yourself!!!!!", so much as "These guys are the face of the Wii. Because they are so versatile in appearance, their stats are straight across the board".
Pac Man.......don't get me wrong, I like Pac Man, just...not much. I haven't played a Pac Man game since...Pac Man. I could argue the whole "He's not a Nintendo character" argument, but he's more of a Nintendo character than Snake. And Snake was actually in Super Smash Bros. I suppose I'd prefer that an actual Nintendo character get in over a character whose appearance isn't so easily associated with Nintendo, as Mega Man is, but I would get over it very quickly, so long as they execute his moveset uniquely.
All in all, it could be worse- I'd rather see six brand-spankin new franchises than a rehash of what we've already seen before.