Music player: I have all my music I want to listen in my SD-card, the stock player won't automatically move to the next track when the current one is over. Annoying and I hope this'll get fixed.
Also a great number of tracks can't be played.
Mail: I haven't been able to test this yet because I incorrectly entered my mail account settings and haven't found a way to reset & correct them yet. Yes I have tried uninstalling & reinstalling and searched from the application settings.
Battery: When the battery drops below 10% the device starts to lag. A lot. The energy usage I hope could be made better, battery doesn't last long enough.