ios5 is ok, the notifications are a lot better, but it's still like a crud version of lockinfo if you ever used that? There's a pull down bar now (dare I say it, similar to android) which is handy. Private browsing in safari is always nice (for when i'm buying the wife a birthday present and I don't want her to find my history...honest). iMessage works like whatsapp, so that's also good. Only works between iPhones though, which is **** as whatsapp works between apple, android and blackberry. Other then that, it's a beta, so a little laggy and crashes a bit too, especially safari. Beta 2 is a lot better than the 1st though.
I think I was still on 4.2.1 before also, 4.3 didn't really offer a whole lot.