It's a personal thing.
I've been running Linux since 1999, and personal www/ftp/email/etc over the same period of time.
But I just bought a .Mac family pack for $90 (don't buy .Mac straight from Apple -- you can get better deals elsewhere) because, to be perfectly honest, I don't feel like messing with all that crap anymore.
With .Mac and iLife, all of the basics of building a web presence are there (and amazingly simple), and you also get some perks like iDisk, which is nice for people who want to back up a relatively small amount of data offsite, and syncing address books and calendars and stuff like that.
The general rule with all things Apple applies here too. Steve Jobs is a benevolent dictator with good taste. He charges a lot, and he doesn't allow much in the way of individuality or customization.
So if you like the way .Mac works, then buy it! If you want something different, there are other solutions out there for much less money (often free).
You're the only person who can judge it, really.