It's 20 gigs of hosting in the cloud, email addy, syncing contacts, emails, calendars, bookmarks ect across multiple devices and a photo gallery that has public and private options per photo album. The remote wipe and find my device features are nice also, but not the whole thing.
I have it because I like that it keeps my mac, ipad and iphone all in sync plus it allows me one stop shopping for sharing pictures with my family across the US.
Yeah, that is exactly the point. MobileMe is perfect for users, who live in the Apple ecosystem. I have two Macs, two iPhones, two iPads, and the web-access, which are all on sync. And it doesn't matter, on which device I change a piece of information, it will be on any device (which is registered and associated to my account) instantly.
I also use the iDisk for storing informations and with GoodReader it's like having an extra 20GB.
I love it.