I really don't want them having access to my personal e-mail either, but I don't consider chain letters and such from friends as personal mail. I'd much rather have them sit on Google's server than my e-mail box, anyway.
Plus, I really don't mind letting them parse my chain letters and serve me ads for "urban legends". =)
I do like the interface, though. I'd much rather login to Gmail than Y! or Hotmail. Any day of the week.