Just a side comment on how 4e is better for free form, low planning, DMs.
That's me. My 'adventures' are usually a bare handful of scrawled notes along the lines of "The PCs go to town. There's some kind of problem, like orcs. They do something about it. I think I want a gelatinous cube in there somewhere. The end." The one thing I *do* prep is characters, so I have a toolbox of things to pull out. I'm never sure how the PCs and the characters will interact or who will be popping up in a given adventure, so I make sure to have a lot of 'em. If I have an overarching plot for a campaign, I will have some BBEGs written up, and have all sorts of things happen which, unknown to the PCs at the time, are manifestations of said bad guy's powers, minions, influence, etc. Seemingly minor NPCs become major ones when the PCs take a liking to them, so I need to know what they can do beyond "hit people". Etc. (And having everyone be good at everything because every skill goes up with level is dull, dull, dull, dull. And did I mention that it's dull?)
4e seems very hostile to this playstyle. For one thing, everything is 'encounter' driven, and encounters need to be heavily set up in advance. I can't just grab 2 CR-appropriate monsters and toss them at the PCs, I need to decide how much XP an encounter "should" be worth, then be sure to add in Interesting Terrain (TM), I must determine when the encounter "begins" and "ends" (difficult when combat and talk intersperse regularly -- if you fight a monster, then stop and parely, then start fighting again, is that one encounter or three? What happens when another NPC walks into the action?), etc. It's not easy for me to distinguish Orc A from Orc B when they don't have skills or feats to swap out. Adding class levels is alleged to be possible, but we've seen nothing on how it will actually work.
In short, I run a world -- not a chain of 'encounters', and building everything from player abilities to monster stats around the idea that the game is constructed out of encounters is very unfriendly to my way of doing things. Maybe if I tried running a game, it would become more intuitive over time, but right now, it's just Not The Way I Do Things.