Hmmm, to be honest I've never been into the whole "Smash" thing even if I like fighting games quite a bit. Seems like a quick cash grab to me, and when it's finally out, it will probably turn out like most similar clones.
To be honest with all the talk of the new console generation coming out before too long and hints about what has been developed, I think this might be both a last minute cash grab, combined with testing to see if they could make something of this sort as a launch title for the next Sony console.
Personally I think Sony's character roster would work better in a more Capcom-like fighter than one duplicating the SMASH format. Opinions vary, but I don't think some of these characters work well together. Capcom always did better making divergent art styles work together (cartoony vs. realistic, and stuff in between) than the Nintendo franchises did, at least to my eye.
There is also such a thing as too silly IMO, having "Fat Princess" as a character is pushing it, especially seeing as she's less a character than a comedic gameplay mechanic. I know "Smash" has always functioned on the absurd, but oddly I can more easily see Kirby fighting Samus (as dumb as that is) than I could see say Fat Princess defeating Kratos.
Of course joke characters seem to be all the rage right now, they DID put Pheonix Wright into Marvel Vs. Capcom despite all common sense. "My secretary tripped and KOed Galactus..."