I can see where eliminating 3E's "A rule for everything, and everything by the rules" philosophy will help, rather than hinder, roleplaying. The best roleplaying is done without rules anyway, as it amounts to acting and storytelling. Those are usually the most memorable parts of the game.
Once I see more details on skills challenges I'll be able to judge how those work, and how difficult they are to run as a GM. From what I've read here my initial impressions are favorable. It sounds like a good method of getting the players to think creatively and to all become involved, rather than having one person make the single diplomacy check and be done with it. Not that we actually ran diplomacy encounters just on a single die roll. They were roleplayed out, with the skill check as a modifier.
What I do feel is lacking somewhat are secondary skills, or background skills. I'm all in favor of dropping many of the truly excessive number of skills from 3.5. Come on, who really took the Forgery skill? Even with a rogue who had a 16 int, I found myself often having to pick and choose among the rogue skills that I could take. There just weren't enough points to take everything I needed to have, much less optional stuff for the sake of roleplaying (even though I did it anyway). Too many skills, too few skill points.
For the next campaign regardless of whether it's 3.5 or 4E, my thought was to come up with some simple means of choosing what skills your character knew prior to becoming an adventurer. Were you trained as a scribe, a ship pilot, a blacksmith, a chef? I don't care so much about the numbers, but having that information about your character's background helps in fleshing out your character to make them seem more real. It provides a sense of who they are as well as encouraging players to make use of that background in game. The reason for making it subject to any rules at all is that I want to avoid the mid-game revelation "Oh, by the way, my character is a master jeweler, so of course I'll be able to get that diamond out of the setting without damaging it" problem.
I may have them choose a single profession and a couple of hobbies, or secondary skills for those who were not wealthy enough to indulge in hobbies. I don't care how *well* someone can sail a boat, only whether they have some experience with it. If so, the rest can be done on the fly.
So yeah, I feel the lack of secondary skills a bit with 4E, but they didn't work right anyway in 3.5, so I'm all in favor of the change. I just have to graft on a couple house rules, but I was going to do that in 3.5 anyway.