That's a list of all features. Which one do Apple users pay for? If you're referring just to bookmarks syncing with .Mac (now MobileMe), the .Mac membership syncs a LOT more than just bookmarks, plus has email, your own website, etc. Syncing bookmarks is one small feature of .Mac, which can also be accomplished with dozens of free services out there, so in that regard, Firefox isn't offering something that can't be had free numerous other ways.
What happens if you do not want to have your own webpage, if you just want to sync bookmarks?
Or what about mouse gestures for fast browsing?
Firefox's abilities are limitless ( nearly ).
If you wish something that does not exist as a core capability you would find it as an extension most likely.
Only think I dont like is that it does not behave like safari when I maximize the firefox window. ( I acts like Windows programs and gets fullscreen )