There hasn't been anything out of line that I've seen. Heck, the man is running for President of the United States, not class president at a junior high school. If he can't take a little criticism then he sure as heck can't handle the job he's seeking.
McCain has every right to point out the differences between himself and Obama, and he has every right to point out the differences between what Obama says and what his past actions have been. For instance, Obama claims he can reach out and work with the opposition to get things done. Problem is, he's never done that, so why should we believe he can, or is even inclined to? He has the most liberal voting record in the senate, and that's saying quite a bit these days. Someone who's voted that far left on every issue that's come before him isn't someone who's shown a willingness to compromise.
As for all the moaning about negative ads, just because Obama's supporters, including most of the media, cry foul, doesn't mean he's being unfairly treated. He's being treated no worse than any other presidential candidate in my lifetime, and a heckuva lot better than most.