Errors from previous editions which got repeated:
1. Focus on tactical combat. D&D has always been a combat-heavy (even combat-focussed) game, and 3e introduced some interesting tactical elements to combat, but 4e might have gone too far. An effort to make combat less "swingy" has turned it into a grind. The powers system, meant to give all classes interesting options, seems too rigid and self-absorbed (using DMG p.42 is generally not as good as just whacking the guy with your encounter power).
2. Inconsistent use of clarifying language and cross-references, and over-reliance an terminology. D&D has always had a lot of terminology and sometimes it is explained well but sometimes it is left to the players to follow the trail of logic (each edition reads more and more like a computer program...). For example, the Reliable keyword. You're expected to notice that keyword and know what it means. Would it have been that hard to add a line about "
Miss: The power is not expended?" There's a similar problem with Sustained -- sometimes the power spells out what that means, but other times it assumes that you know the specific definition of Sustained Duration. Here's a thread about that:
http://www.enworld.org/forum/d-d-4th-edition-rules/254646-sustain.html
3. Math Soup. Every round of combat there's a lot of, "Wait, so I'm at +2 for combat advantage, -2 for cover, +5 for the
righteous brand, -1 for being in the aura, oh and I'm -2 until I save because of that other thing..." Situational bonuses (cover, combat advantage, etc.) are one thing, but when you layer on the dozens of powers that grant minor bonuses and penalties, it becomes a real hassle.
4. Superior weapons. If you're a melee character, there's probably a superior (formerly exotic) weapon that you should be using because it's better than your military (formerly martial) weapon. By most definitions of game balance (which I will not repeat here), this is imbalanced.
5. Strength+Armor. 4e doesn't even have Weapon Finesse for the poor Dexterity-based combatants. Combat Training is nice, but it's only for basic attacks, so it sucks for warlords and paladins and so forth. And while light armor got a really nice boost, it's still risky to go unarmored (unless you're an avenger) -- even the wizard gets a tremendous benefit from upgrading to leather. D&D has always been about "fighting men" with strong sword arms, but I think the genre source material has enough swashbuckling ninja fencers to justify Dexterity-based combat for people other than rogues.
-- 77IM