TheDigitalLifestyle.tv: Why buy .Mac these days?: "Sync & Backup: These two features almost don’t deserve any attention. Backup has been replaced by Time Machine or just an external HD. Sync is not worth any part of the $99 price tag and thus deserves none of our attention or yours."
That's funny. I find the sync features the most compelling reason to purchase the .mac service. I agree that most of the other basic services of .mac can be easily replicated with free offers from various suppliers. But I disagree vehemently that the sync proposition has no value. As mentioned, I think that it has little value for those who currently only own one mac, but if you have multiple machines or use multiple user accounts, it's irreplaceable.
If my suspicions are correct, then the .mac service will soon have even more value for those people with a Mac and an iPhone, offering over the wire syncing and cutting iTunes out of the loop (except for music and video I would guess).