I find the MediaPlayer main controls on the lockscreen very useful, but I want to suggest a little change and to report some problems:
* Suggestion: the MediaPlayer lockscreen shows a little thumbnail, the title of the song playing and the title of the album. I think that it should show Artist name and song title (or Song title and artist name), or -at least- an option to choose what info to show on the lockscreen

* Bug report: sometimes I create a playlist, then play it, but when I want to skip a track, the MediaPlayer on the lockscreen disappear, the music stops and the playlist I've created is lost forever (if I didn't saved it before). It doesn't happen all the time, but I guess 4 times out of 10 [which it's a lot]

* Bug report: if I pause a playlist for a while (for example: I arrive to work, school, or just go to sleep) and then press play after that while (sometimes 20 minutes, sometimes 8 hours) the MediaPlayer on lockscreen disappear and the playlist I've created is lost forever.
I experience these two problems since always, not only on the last version of TC for Android.
My cellphone is a Motorola RAZR D3 (XT919), Android 4.1.2 (core 3.4.0), and I don't use any task killer.
Cheers!