I agree that I think it played out really well, albeit this season as a whole has been far too rushed and therefore the arc has felt a little less natural than it should have done. Anyone who realistically didn't expect the Mad Queen story arc to play out can't have been watching the show. It's been hinted at constantly and it has only been a serious of wise advisors (Jorah, Tyrion, Varys) who have kept her from acting as her instincts dictate. I agree with the above that the loss of them / mistrust of them is what ultimately caused her to go off the rails. Without their support it would have happened much sooner.