It might be just me, but its kind of annoying to see somebody posting on my profile and then have to go to their profile and reply by posting. It takes more time than I think it should (although it my be my problem) and you can't see the whole conversation at once.
I think there should be a way to reply directly to the messages on your profile without having to do that.
Also, the private messages are really troublesome, especially if you are having an actual conversation and it takes really long to get the messages. I think there should be an instant messaging thing.

Sorry if I complain too much

That's it.