It doesn't at all play like Super Smash Bros. at all, though.
I'm telling you guys, it plays like Power Stone 2
The Konami game that does play like Super Smash Bros. (but not as well) is Dream Mix TV World Fighters.
Power Stone 2 was awesome, and yes, it totally does.
As for another Castlevania fighting game, I can see it going either of two ways:
1. A 2D fighting game akin to King of Fighters or Guilty Gear (preferably done by the same sprite artists)
2. Another 3D fighting game akin to FF: Dissidia or Power Stone
Off the cuff, I prefer the first. They'd be able to maintain the familiar, attractive dark gothic, Romanesque art style of Symphony and its off shoots, while playing in safer territory. IMO, theme-based fighting games need to play it safe when it comes to fighting mechanics so that people who can't play a game solely for its characters and theme still have a reason to play.
On the other hand, if they fix Judgment's many problems, I could see another 3D fighter being good. Taking a page out of the Dissidia notebook and freeing up character movement, while perhaps changing the damage system to something akin to the brave system, would be awesome. It would also leave room for the loot system that so many love. Obviously the game would need to be a lot less floaty than Dissidia, focusing more twitchier ground combat, but that's why they shouldn't throw away the Power Stone format entirely. Outside player combat, you could have monster levels where you'd have to fight multiple Castlevania monsters at once.