I have been using GMAIL for about 3 years now. I started using it for the large mail sizes and the amount you an store. From that angle it is great. From a UI stand point and a email management stand point it’s a complete wreck. All of your mail is stored in one place and there are no folders of ways to manage it better, other than with filters or views. I don’t like all the filters of views, I like folders and the everything in one bucket aproch is killing me. I lose things, the treads are hard to track and I am starting to really use it a lot and love the calendar and documents side of it, but absolutly hate the GMail interface.
I am moving to Yahoo Mail, and now I have to make sure all my mail is routing and everyone changes how they get in touch with me, what a pain, but at least Yahoo works the way I thing.