Fair discussion above. But as Klaus mentioned, that end of season collapse is something all Arsenal fans must hold whenever weighing out an opinion on Emery.
I just happen to think that rather than poor tactics/patterns or lack of resources as Klaus and Claudius' posts suggest, it was Emery's total lack of premier league experience, and general naivety in the face of away matches to the Watford and Everton types. Or more specifically, an innate inability (whether its his demeanor, the language, his funny accent etc) to motivate this particular group for those particular games, which is a way bigger problem, seeing as neither of those are going away.
So, the important thing to look out for, for me, will be their performances in those fixtures. If he hasn't quite obviously made steps towards fixing whatever was at the core of that April collapse then he just won't be successful here.