Vishy saves his best stuff for the WC matches so you cannot go by what you have seen when they played in the past.
If his best stuff is what he showed against Topalov and Gelfand I don't think it is much different from his play in other events. He did impress a lot against Kramnik, but those days he impressed just as much in tournaments (winning Linares 2007, World Championship 2007 and Linares 2008). I think Anand just has dropped a lot in playing strength the last five years and will find it difficult to make this match as even as those last two.
I am on the fence both in who I think will win and who I want to win. Vishy saves his best stuff for the WC matches so you cannot go by what you have seen when they played in the past. He is excellent at WC prep and has tons of experience. Carlsen shows he can win from some drawn positions if his opponent is inaccurate. He is not perfect as he proved in the last game of the candidates when he lost and had to rely on Kramnik also losing. Carlsen has no match experience and was arguing hard against them for the WC, maybe because he does not like the idea. Someone can correct me if I am wrong, but I don't think we have seen a lot of novelties from Carlsen making me wonder what it will be like if he tries it for the first time now. I don't think anyone should count out Anand just yet, but even with all the things going for him, Carlsen may be too strong already. If not, Carlsen will have his day even if he loses this time.