According to Treantmonk and Colby of D4 Deep Dive, who do a general discussion of the new PHB in
videos on each of the
other's channel, the floor has been raised, but the ceiling lowered ... slightly. They come at it from an optimizer's perspective and some of the main ways to get high burst damage, like Divine Smite, the -5 for +10 damage feats, etc. have been limited or outright nerfed. OTOH, some of the more abuseable spells haven't been touched, apparently. But classes that were previously considered weak are now much better, they sounded particularly happy with the new Monk.