The problem with 4e is it dropped everything else. The fixes to combat make it much more accessible to a new generation, and that's great, but a D&D session shouldn't play like an MMO. You need just as much richness in the setting, in open-ended exploration, in diplomacy, in absurdly over-engineered traps, and so on. 4E got some pieces very right, but it's too tightly wound IMO - too much focus on combat, and especially on well-balanced combats. It's a poor system to accommodate cleverness and tactical elements not captured by player abilities.
4E adventures tend to be a set of very-well-balanced encounters all very level appropriate for a party, but that loses much of the charm of D&D. 4E is poorly suited mechanically for "crazy plans that just might work" to take on foes far out of the party's level range (unless they're scripted into the module). E.g., the party wants to kills a group of foes far more powerful than they, so they gather intelligence by diplomacy, intrigue, and seduction, discover a good time and place for an ambush, arrange to blow up a cliff face to drop an avalanche on the foes as they walk past on a marrow path, then attack before the dust settles. Pre-4E, it's fairly natural for a good DM to figure out how that all works and run a fun session around it in a way the players find fair. In 4E you have so little to work with for any of that, unless it was part of the script.