MobileMe Calendar finally got me past the occasional frustration and issues on my calendar sync solution. They did this by breaking my Rube Goldbergian solution completely and having me setup a much simpler system. My prior solution was like this, Google calendar for my work domain was my main calendar. But when I first got an iPhone there was no two way sync between Google calendar and the iPhone, but I could sync using MobileMe between my phone and my desktop. So I got a piece of software called BusySync (which I later upgraded to BusyCal), this would sync the Google Calendar to my desktop iCal store which would then be synchronized via MobileMe to my phone. And it mostly worked. I had my calendar on the web, on my desktop and on my phone and could make changes in any of those 3 places. Although sometimes it would do weird things and I had to keep BusyCal always running on my work computer to keep everything going.
Recently I unthinkingly upgraded MobileMe to the new Calendar. Which of course broke all of that for various reasons. And this turned out to be the best thing I could do, as now I have a much simpler solution that seems to accomplish the same goals and work more reliably.
Now my phone synchronizes with the Google calendar directly using ActiveSync. And my desktop and laptop BusyCal synchronize with Google calendar directly but only need to be running when I need a calendar there. So MobileMe solved my occasional calendar problems by becoming useless for me.
At this point I'll have to evaluate if there is any point to keeping MobileMe at all or if I can simply use DropBox to keep the other things in sync that MobileMe does for me, and I certainly don't need another email account, or IM account and their iDisk solution is a joke compared to the ease of Dropbox.
Is there any other value to this service I'm missing?