It's a pretty no-brainer answer, gameplay. So I'm instead going to tackle the question from a different angle.
Will the graphical style (style trumps fidelity) impact my interest in a game? Yes.
Being an artist I tend to favor games that interest me visually over games that have a less cohesive, or maybe even boring, style. Games in the latter camp will most likely be glanced over and maybe picked up later.
But ultimately this all hinges on gameplay of course. If a game from the latter camp is actually really, really good and I hear about how good it is, I'll likely want to try it out then.
The reverse applies for games that do appeal to me visually. Example, I looked forward immensely to Asuras Wrath because it looked badass as all hell. But then the demo was released and in truth, as a "game" it sucks and I will most likely not get it unless I find it dirt cheap somewhere.
Graphical style matters, gameplay matters more.