Well here goes one that might get me in trouble.
Overrated: Dungeons and Dragons. So, yeah I started with D&D, I appreciated that it got me into the hobby but I never got the whole reference that people hold for it. Now, I'm not saying I didn't have lots of fun playing pretty much any edition of D&D but I still found the flaws and to me it's just an RPG just like any RPG and not some phenomenon.
And no, it can't do everything. No version of D&D is all things to all people. It can only do a few certain types of Fantasy and I am sorry to say, it is not the greatest RPG of all time.