So Sony's putting out a Super Smash Bros. clone, and I mean that in the kindest way possible because I love me some Smash, but the reason Nintendo can pull that off is because they have so many iconic characters. Sony, not so much, and I think the roster they've already announced shows that: Kratos (of course), Sly Cooper, Sweet Tooth (Twisted Metal), Mael Radec (Killzone 2, and also, seriously?), Fat Princess, PaRappa the Rapper.
Patapon and Ratchet and Clank assets will at least show up in levels, if not as fully-fledged characters.
A lot of great characters have appeared on the PS3 and in PS3-exclusives, but not a whole lot of those came from first party games. Let's be honest, all they need to do is tap Final Fantasy 7 and they'll sell a few million copies on launch day, and fans have already been asking for Old Snake. Personally I'd like to see some of Team ICO's characters on the roster. But when they announce a generic space marine from their flagship generic FPS, it sounds like they're already scraping the bottom of the barrel.
Secondly, Super Smash Bros. games are known to contain a ton of content, which is one of the reasons we only see one per generation. Maybe Battle Royale will too but so far I'm not really seeing it.
Guess we'll see more at E3, but at this point I can't help but wish they'd just tapped Capcom to make a new Power Stone game.