It is nice that it doesn't seem as much as a foregone conclusion as in recent series, I think. I've found the past few CBB finals quite boring because the winner was just so obvious (and I wasn't particularly interested in said winner, either).
I have to say though, I don't think all of them have a shot - I really don't think Michelle or Keith can do it. I'd say it's between the two Katies, with Calum the dark horse.