I've seen so many of my favorite series of games change art styles over the years. Ultimately, it doesn't really make much difference to me. Like say Final Fantasy, it will be story, gameplay/battle mechanics and level design that determines how much I like it.
I think the only time I was ever upset about a change in art direction was for Zelda: Windwaker. Even then, that was at first and by the time I got on to the open seas, I was over it. I don't mind it at all now. I think the biggest reason for hating it back then, was that I was expecting something like what Twilight Princess looked like (considering that was the art direction they originally showed for it.)
Either way, to each their own.