What I would like to see is a pricing comparison chart. I've never looked into pricing with other vendors, but I believe there's nothing here that isn't offered elsewhere. I can only assume that for all you get - web, email, 100MB storage, calendar - $99/year is competitive and fair. (As far as I know, a comparable service is not free anywhere. Feel free to show me where I'm wrong!) Apple's added value is the smooth integration with OSX.
Here's what would concern me. How high is the switching cost if I decide to switch vendors? Mail.app works with any ISP. Will iCal and iDisk Utility also be workable with any other vendor? That might be too much to ask for, so I would be cautious when making .Mac my "home away from home" and conscious of not developing too tight a dependence on it.