Honestly, it hasn't been online and consistently available since the service has been available. I had a csr chat yesterday in which I was basically told, "Yeah, we know the service is horribly unreliable and basically useless. It's likely not going to improve for some time."
Usually, if I log out and log back in a few times, it eventually works. Also, I find that if I can't get the iphone/ipad app to work, if I try to log in on my computer, the app starts working, and vice versa. I can almost never get one to work without trying to log in to the other, though.