Character Generation and Setup
In a sense, this is one of my biggest complaints about 4e in general. I'll admit that I haven't spent a lot of time working through the books, but I truly cannot tell why certain things work excellently and others just don't. I was playing a barbarian and a friend was playing a sorcerer, both classes that are described as being Strikers, but I was doing something like double his damage on at-wills with pretty average rolls. I looked at his sheet and couldn't for the life of me figure out where I was getting the extra damage apart from the fact that I'm wielding a d12 axe and he's using smaller dice. I suspect that the fact that he's ranged has something to do with it, but even that is more conjecture than anything else.
All the same, character generation took quite a while despite the easier loot choosing. We were third level and received three magic items each which I'm still not entirely positive makes sense. Unless I'm greatly mistaken, the game doesn't give that many magic items through the course of a single level. Fourth edition seems to have a lot of these weird little quirks that I'm not entirely certain why they went that way.
The Game Play
Getting to the hunting lodge and getting into conflict with the boars went pretty much as I would expect from a 3.5 game (or really any fantasy RPG where such a thing could go down). Unfortunately, once we were in combat things really slowed down. Even though we were dealing out pretty massive amounts of damage with two strikers out of four players it took a huge amount of time just to get through this one battle. Indeed, we didn't even get to the mines because so much time was spent taking out the pigs. This isn't to say that the combat wasn't enjoyable, it was really fun looking at encounter powers and switching between at-wills to max out my damage while still enjoying delicious temporary hit points. The barbarian was a blast and my damage output was out of this world. Getting together with the guys is always a ton of fun and we had an excellent time strategizing and employing powers together to get the most bang for our buck.
The trouble I think came as something of a systematic thing. Before we were in combat we were roleplaying our characters and drawing out cool things about the world. Our minotaur compatriots were apparently headed for the minotaur army off to the east and in an almost disaster inducing backstory idea my barbarian greets the sunrise with a roar of acknowledgement. There was a fair amount of silliness but that's kind of our M.O. Once we got to swinging weapons this really petered out. In other games we've had lots of in-combat RP, but with the exception of moments when we tactically were able to slow down the onslaught of pigs it was kind of just a litany of 'I use my Description Verb on the boar.' With the exception of making an intimidate attempt which finished off the combat we more or less moved about, used our attacks, and ended our turns.
D&D 4e Application
I keep on talking to people who started out with 4e instead of an earlier D&D version or Pathfinder and am shocked each time that they say that earlier editions were more difficult to play. Sure, you've got a host of spells to keep track if you are a caster, but in 4e everyone has a host of spells to keep track of. Instead of rolling and having basically one thing that you'll add to all rolls I had something like 3 possibilities of bonus for my to attack roll and 6 possibilities of bonus for my damage roll. It's not horrible to keep track of, but it's enough that I forgot to keep track of things pretty frequently.
The bigger issue that I think 4e has is the difficulty of weaving together attacks with roleplaying. If I roar and bring down my axe into an opponent in Pathfinder, I'm probably attacking them. But I should be exact about what I'm trying to do ahead of time in 4e given that Howling Strike and Avalanche Strike are both possibilities with that kind of description. In the end, it just seems like it's easier to say 'I use my Howling Strike' and roll to attack. Because of this, I don't think that 4e works well for your standard Party vs Dungeon experience.
Instead I think 4e could be used really well for potential supplements to an adventure. What I'm picturing is a party who manages to raise a small army, a band of thugs, or some other larger group of characters. After a little tinkering to lower HP (because this can't take all night), you set up the field and play it as character controlled squads. Maybe your archers can grab a couple of At-Wills and the archer PC can control them, ditto for the other classes. Building up your forces and choosing their different powers could be fantastic especially when a daily (perhaps a weekly for a longer-term battle?) can change the tide of battle so definitively! The apparent harkening back of 4e to the age of wargaming I think explains a lot of how it works and what it would work best for.
I've got an upcoming game that I'm probably going to use an amalgamation of Pathfinder and Eclipse: The Codex Persona for. I'm thinking that if things get into a war-time sort of feel, I'll add in a little flavor of 4e. It's honestly REALLY cool that a raging horde of barbarians can charge someone if they take their target down! That's awesome! But when I come to the table for normal play, I don't think 4e is ever going to be my first choice for Party-Based gameplay.