Gmail is okay. No real negatives. I used it long enough to get used to the unique interface, but ultimately decided that I like neither threaded views nor perpetual archiving. In the end, I went back to Yahoo! mail.
Some of that may be because I use the My Yahoo! page and use Launchcast Radio (a Yahoo! service), and I find Yahoo! Groups to be significantly more useful than Google Groups. So, I'm logged into Yahoo! a fair amount, anyway. Why have my webmail somewhere else? I've got my own domain, so the only thing I use Yahoo!/GMail for is lists or potential spam sign-ups, anyway. I can't imagine using either as my primary email account.
Actually, it's funny that I use so many Yahoo! services, considering I used to hate them because their search engine has never been able to return what I was looking for.