I'm going to renew .Mac only, and only, if I get some kind of deal that pulls the price down somehow to a reasonable $50 or so. $99 is too much for too little.
I happen to be integrated into other workflows with Office using Entourage, so a lot of the address book and synching capabilities of .Mac are irrelevant to me since there are no conduits to synch my Entourage information with .Mac. If that capability existed, combined with increased iDisk speed, then and only then would I conider a full-price renewal.
I also wish there were some kind of data backup guarantee--if I store backup files on .Mac, I'd like to know someone guarantees they'll survive earthquake, fire, and hackers alike. Until then, I don't see the advantage to the iDisk over, say, Yahoo! briefcase.