Actually, this chapter provred he IS in control for most of the time. When he went all puffy, Minato stats that he still isn't used to the Juubi. That only makes sense if he is in control, and couldn't handle the Juubi perfectly in that Scene.
I don't think he is if obito was in controll I think we would of had some talking from him already instead of juubito just going on a rampage trying to kill naruto and destroying anything that attacks him or gets in his way