It depends what you want it for, I guess.
Web space? Not worth it.
Email? Not worth it.
Fabulous syncing? Possibly worth it.
I'm new to this syncing thing, and I quite like it. I dont have a .Mac account because I need equal Windows compatibility too.
For favourites, I have been using
Flock & a service like del.icio.us called
Shadows that is fully integrated into Flock. So, my favourites stay updated on any of my PCs or Mac. As for syncing other data, not so sure. Calendars - Google calendar & iCal worked last time I tried.
The iDisk replacement comes from
Box.Net - Gives you a gigabyte to sync files between your computers. I use it as a simple way to transfer word documents etc between desktop/laptops for ease when I'm out and about.
As for email and web space, I have my own server space for a few pounds a month - Much cheaper and much better than .Mac.
So its not all bad .Macless, with a few hours of tweaking you can emulate most of the services.