Dot Mac chumpin here too
I've always felt that .Mac offers me no single, invaluable must-have feature, but as a home and work Mac user I happily pay the annual fee for a few conveniences worth at least tens of dollars each -- particularly the sync of Safari bookmarks & Address Book. And I don't mind if I'm not getting every nickel's worth directly; as an AAPL investor I think it pays to know Apple's products first hand where possible.
(With a typical North American home internet connection of under a hundred kbytes/sec upload speed, I never use more than a few hundred MB of iDisk, so the standard-plan 1 GB ceiling is plenty for me.)