The result of the new AE system is people allying Austria every game, and then later allying France.
You can completely ignore AE when you have some huge allies. Coalition of 20 nations? Whatever, I've got two great powers coming to my defense.
I'm running a game as Burgundy presently, and I'm having mixed opinions regarding the AE system. I have spent the last 200 or so years with AE always around 70 with most nations of note. France and Austria have spent the entire game in coalition against me, with the other members being various minors in the HRE and northern Italy. I can't declare a war against anyone without someone being allied to someone else that's part of the Grand Anti-Burgundian Effort. So, AE is gained far too fast and lost far too slowly. But that might be a side-effect of the fact that I've expanded inside the HRE a fair bit, and Austria is my rival, which means that they probably get some extra AE off me. On the other hand, I can completely bypass coalitions by the fact that Bohemia, my bestest ally in the world, constantly calls me into wars against various HRE states, which allows me to occupy the various secondary war members and be graciously gifted territory when the Bohemians, who are the war leader, sue for peace against them. So, the results are that for the last century or so my AE levels have steadily increased to the point that France has over 150 AE against me and the average AE score in the HRE against me is in the 70/90s without me declaring a single aggressive war myself for who know how many years [except one, where I directly tackled France [or what's left of it, which would be more or less the western half of Aquitaine in CK2] and Austria for control of Toulouse and the vassalization of Milan and Savoy.
The point is, AE increase A LITTLE too fast and decays FAR too slowly, at least whenever the HRE is concerned, but its effects are hardly as catastrophic as people say. There's no "annex two provinces, get coalition of half of Europe", but there is "annex two provinces, your rivals enter coalition against you and will probably never leave again unless you spend 60 years or so without another conquest, at which point they will leave, but will join again after your next war" and "by the way coalitions can be completely bypassed if only you got an ally that is trigger happy".