Being able to just type in the random things you remember from a url / title (I think it combines them) and have FF narrow down the alternatives, -fast, is something I haven't found in any other mainstream browser.
Another aspect is it doesn't automatically send everything you type to google (I don't worry to much but it is a nice touch.) Maybe the average user is confused by having a separate search field in addition to the address bar but I like it. (And yes, you can search from awesomebar as well, although there is no suggest feature.)