4Es main problems:
1) HP bloat caused combat encounters to take even longer. They were already a sizable part of D&D
This killed it for me. I remember one fight we had with a solo/elite/whatever. We were around level 2. After fighting the thing for about 15 minutes one of us scored a critical hit on it dealing some ~40 dmg.
Everyone was cheering and we asked the DM: is it bloodied?
DM: uh, no, not yet.
The rest of us: fuck this shit!
The thing had some 150 HP in total. It's not like it did anything special either. It was just a big orc with an axe who occasionally could hit two enemies at the same time, but every power he had had some ridiculous name like SAVAGE SMASH or FURIOUS FIST or some shit.
About healing surges: their main problem was that it was a rigid mechanic. For example in pre 4e you could easily make a house rule so that the party could regain all of its HP after every battle or a night's rest. If you wanted a more action oriented game you could easily do that. On the other hand, in 4e, if you want a more realistic approach it was almost impossible to do so, because the healing surge mechanic is so rigid that it would take heavy tinkering to make it work.
Actually the whole game felt very rigid. Often times I felt like I was playing a video game.
For instance: I once wanted to make a fighter who specialized in ranged weapons (because this archetype is one of my favourite to create in the IE games). Lo and behold it is impossible to do so, because every single power that a fighter has requires a weapon to be wielded. But let's say that the you could talk with the DM about it and he would let you use a ranged weapon instead of a melee one. That's doesn't help either because most of the fighter's powers are all about taking aggro and tanking, which is retarded for a ranged specialist.
I admit was very excited about it at first, and even 'whiteknighted' but soon the flaws became apparent and I stopped playing it. Oh, well good thing I didn't spend a dime on it.