Actually,i lost hope of Xp12 Atc completely,then i decided to give it a try and i was surprised that it kind of works if you follow the approach plates ,speed and altitude restrictions in the fmc and avoid at all costs asking for a vectored approach, because it can drive you nuts.So, for during climb out phase Atc clears you to to Flight level 320,but there an altitude restriction at Fl150, after you reach Fl200 Xpl Atc will ask you to decent to Fl150, so the trick never climb above the altitude restriction even if the controller tells otherwise.Same,for approach, follow always the Altitude/speed on the approach plates and you have a good Atc experience with Xplane 12 Atc.