The problem for me is recasting at all. I've known these characters played by the same people my whole life. Quinto doesn't have Nimoy's chiseled, stoic, and almost fearsome look. But neither does anyone else I can think of, and it's obvious that casting unkowns wasn't on the table, so he's about as good as it's going to get. I look forward to seeing what he does with the part.
Again, I go back to Superman...
Brandon Routh and John Newton may have resembled Chris Reeves alot... Christopher Reeves looked NOTHING like George Reeve. Dean Cain, Gerard Christopher, and Tom Welling and not exactly lookalikes...
At least 8 different actors have played Superman in movies and TV, and he has been drawn by hundreds of different artists. This has not diminished Superman. Spock > Nimoy, Shatner < Kirk.