The Pebble app/iOS app syncing used to be buggy as hell (retrying a few times might get it to sync). The updated iOS app seems to sync reliably now.

As for sleep tracking, as far as I can tell you have to push a button at bedtime. Don't care much about sleep tracking, so I haven't researched to see that my assessment is correct. Still, not a big deal to me when I do use it.