Well, I've played fourth edition D&D for about 15 hours, using a couple of level 1 characters, with two different DMs. Here's some compliments, criticisms, and concerns on the new system:
Character creation is very different. In past editions, you relied on multiclassing and prestige classes to define your character, but now it's all about "powers" (essentially spells unique to a particular class). It's nice that even the fighters get to make meaningful decisions in combat besides "I swing my sword," but it sort of dilutes the skillsets of some of the other classes (a first level Wizard in 4E only has so many tactics). I think the addition of new classes, as well as alternate powers and paragon paths for the existing classes, will be critical for the longevity of the game.
That said, there are at least a couple of viable builds now for each class, in terms of ability scores and power combos. In my case, I could play an effective paladin that wasn't an 18 Strength goliath, since there were plenty of skills that use your Charisma modifier for the attack and damage roll. I do expect the ability bonuses to eventually be overshadowed by the inherent level bonuses you get to all of your skills and attacks; for the first few levels, though, it's all about the scores.
After seeing the skill challenge mechanism in action, I'm more convinced than ever that designing a good skill challenge takes more time than designing a comparable combat encounter. Without the proper context, skill challenges can be as banal as rolling up multiple skill checks and comparing successes and failures. In the future, I think I'll just plainly announce when something is a skill challenge - much like how "roll for initiative" is a verbal signal for a beatdown.
The character sheet needs a lot of work. Your character's powers are supposed to be written on page 2, but there is precious little space for them, and they're really important enough to be on the front page. I suspect people new to D&D, and perhaps new to tabletop RPGs in general, will find it difficult to use these powers without having the full text of the power right at hand to give ranges, effects, damage types, etc. That means a lot of flipping through the PHB, unfortunately.
Combat, which has always been the core of D&D, is interesting in 4E. Healing, for instance, is simplified greatly in that you'll probably always be at full hitpoints before a fight begins, thanks to "healing surges." Once the fight's on you have limited ways to regain hitpoints, however, especially if you lack a cleric or healing potions. On the administrative side, I believe some of the "lasts till the end of your next turn" skills need to be reworked. It can be a lot to calculate, although not as bad as the variable rounds that had to be rolled and kept track of in previous games.
While I understand the rationale behind simplifying the skill system, there were definitely a few gaps when we played. At one point in a game, we had the opportunity to tie someone up for later interrogation. There's no "Use Rope" skill, however, so we kinda had to fudge it with a Dexterity vs. Reflex roll and a subsequent Strength roll for the prisoner. It all worked out okay, but less improvisational types will not like the rules-light approach to noncombat adjudication.
There's still a lot of time before you can pass a final verdict on 4E. For one thing, I still need to DM a 4E game. But so far, and at the very least, I think I've gotten my money's worth out of it.
