(Also, last.fm is very picky about scrobbling, making using it a hassle.)
I've heard a lot of people say that, but honestly I've only had a problem once that I can remember (and I've been using it for almost 3 years now) and updating my software did the trick. I like it.
You have to go through contortions to get an iPhone to scrobble (you have to mount a dummy "iPod"), and you essentially have to "check out" the phone. That is, if I've played a song on the iPhone that I would like to have registered, I can't play anything at all on the computer until I have synced and scrobbled all the iPhone tracks. If I do play something on the computer before that, all the phone plays are lost. Once something is scrobbled for 1pm, for instance, nothing that was played before that on a mobile device will scrobble once you sync the device, even if at no point were both devices being used simultaneously.
I'm not sure if it's like that with a regular iPod, but it is with iPod touches, too.
So, that was my big problem. Plus some other psychological nonsense I have about obsessively tracking and keeping data accurate to an unhealthy degree.
