I love the new feature in iOS5 to be able to see notifications on my lock screen, this is something I've been waiting for for a long time.
However, I'm disappointed with the implementation. Push works very unreliably with my iCloud account on my 4S, which is a disappointment. But when new messages do get pushed to the phone they also appear as notifications on the lock screen. So far, so good. But since I'm on my Mac all day long, I almost always end up checking and replying to emails on my Mac. When I pick up my iPhone to leave my desk, what I have is a lock screen full of emails that arrived and were already deleted hours ago. How does this make ANY sense?
Perhaps it's related to the problems I have with push: emails seem to be pushed to the iPhone when the unread count is 0, but at some point they stop rolling in, and the unread count stops reflecting the real unread count as per my Mac. So if I have 5 new emails showing on my iPhone, and I go to my Mac to check and delete them, they never go away from the iPhone and new mail stops being pushed.
I'm using, of course, iCloud for everything: contacts, calendars, mail, etc.
Push was unreliable for my on my iPhone ever since it was introduced. Now that lock screen notifications follow the same pattern, I feel really let down.