Here's what braincraft over on RPGnet had to say:
PHB2 (Electric Boogaloo): The Avenger - RPGnet Forums
The Avenger is Love. Or Hate. Something like that. It's Batman, anyway. I am so tsundere for this class.
I just picked up PHB2 today, and I've only had enough time to really digest parts of it, but I'm really impressed by what I've seen so far. The Avenger looks like it manages to be a really interesting class, which is really the most important thing. Let's break it down:
Avengers are clothies, but get a rough analogue to Swordmage Warding. I get the feeling Armor Proficiency is going to be basically mandatory for these guys, but Armor of Faith and their reliance on Dex/Int keeps them in light armor. They have a surprising number of HP and Surges; less than a defender, but more than any other striker save the Barbarian. That's probably to make up for their lack of armor, even though they look like frontline types.
The striker feature is Oath of Enmity (hereafter OoE). You pick a guy and get to roll Melee attacks twice against it. It differs from the usual striker feature in that you only get one, and you can't open up a new can of whoopass until you're done with your first. This makes a pretty huge difference in terms of tactics, as Avengers have limited ability to adapt. Once they're on track, they kind of have to stay the course... which is fitting, one supposes. Of course, they also get tons of powers that help them stay on target, so it's not all that bad. It's also limited in that the target has to be the only enemy adjacent to you, so positioning is pretty key.
The reroll stacks just fine with Elven Accuracy and the Deva racial power, so you can get some pretty sick probabilities there; for all that there was some pixelbitching about it not being as good as other striker damage features, it's really, really nice for landing those important Daily and Encounter powers. The problem, of course, is that it only works on Melee attacks, so it hampers an Avenger's ability to sideline in AoE or sniping.
An Avenger's Censure gives them bonuses to damage based on stuff. Censure of Pursuit gives them +dmg to their OoE target if it tries to run from them. Censure of Retribution gives them stackable +dmg to their OoE target if anyone tries to horn in on their action. In both cases, they're punishing their target for trying to escape his punishment, but the two builds end up being significantly different; Retribution spec is more about control and denial, while Pursuit is more about relentless agression and rushdown.
They also have Channel Divinity; in addition to whatever applications they might have from feats, they can burn their channel to give an ally an attack reroll against their OoE target. They also have the standard divine class undead-raping channel.
At-Wills:
Bond of Pursuit lets you shift to follow your target.
Bond of Retribution causes an autodamage effect against anyone who attacks you except the target.
Overwhelming Strike is basically Footwork Lure, but it's pretty good when your class feature demands precise positioning.
Radiant Vengeance is a ranged radiant attack vs Reflex that gives you temp HP. It's kind of like the striker version of Sacred Flame.
It's interesting that you have at-wills that sort of emulate the effects of the two Censures, so you can either have an at-will that enhances your Censure or one that gives you some of the benefits of the other Censure. Or both, I guess.
Overwhelming Strike seems pretty important for making sure you get your OoE reroll, and Radiant Vengeance helps you out by giving you a source of radiant damage on demand and letting you target another defense, as well as covering what would otherwise be a bad range for you. The temp HP are okay too, I guess.
All in all, there aren't any strictly bad at-wills here, and the limited selection actually means something for any build (as opposed to, say, Rangers, who pretty much just need Twin Strike and whatever else).
As for the other powers, I'm impressed that they managed to write so many interesting and unique powers while maintaining a relatively tight theme. Avenger powers are all about hunting down your target and keeping everybody else from interfering. They have some really nice powers (like Distracting Flare, which lets you do the Batman disappearing trick at 2nd level), and going through in detail I found only maybe one or two that weren't awesome in some way. The Avenger bag of tricks is both deep and broad (like yo momma!), including tons of shifts, teleports, some invisibility, and painful control effects that follow your target. They have access to a lot of damage types, with Thunder, Fire, Lightning, and Psychic damage all being well-represented.
I cannot wait to take this bad boy out for a test run in an actual game.
PHB2 (Electric Boogaloo): The Avenger - RPGnet Forums