I just move my own site to MobileMe, since it came with my new mac... I never used .mac before and I was intrigued. I have to say that iDisk, for example, looks and almost feels like an attached hard drive if it were not for the time delay it take to copy content to and from it. However, the interface is as smooth as I have seen it and does what GUIs are supposed to do: hide the complexity and disappear in the OS.
I have not (yet) experienced issues with Mobile Me as I am only using iDisk. So technically I have not tried any of the apps depicted in the above icon! LOL