I finally got my copy of PHB2 last night and read through it. The new and additional races and classes are welcome, certainly, but I have some issues with the way the Primal Power source works and how some of the classes are . . . classified.
The power source itself is cool and I think can really add some flavor to a party - as long as they stay in the natural world. A tenuous connection is mentioned between the natural world and the feywild and, assuming I was reading it correctly (it was late), they tried to extend that connetcion to include the planes and the Astral Sea.
Personally, I think the developers stretched this a little beyond reason. Obviously primal powers would work normally for the world/plane/reality from which they are granted. For something like the Feywild (and possibly the Shadowfell), I would say yes . . . but there would be some distortion or reinterpretation - just the Feywild and Shadowfell are sort of reinterpreations/distortions of the natural world the PC's inhabit. The powers would work, but not necessarily in the same way. I do not see how the powers would be able to extend beyond the reality or plane in which they were granted. It's sort of like going to Neptune, but expecting to operate within the same gravitional and atmospheric parameters of Earth.
Imagine the roleplaying opportunities if a character arrived on a new plane only to discover that all their special abilities no longer worked. Clever thinking, basic attacks and the support of their party would be required to survive until they found their way back home . . . Ah well. It's nice to think about as a fledgling DM, but a player may not enjoy it so much. As long as such forays were reasonably short, I think it'd be fun.
Anyway, on to the primal classes!
The Druid, Shaman and Warden definitely feel like they were all cut from the same cloth - variations on a theme. The Shaman uses a spirit-animal-guide-thingie to carry out most of their attacks, while the Warden can draw power into themselves or exert natural forces upon a foe to stop them cold. The Druid is sort of a mixture of both, but also something different. It almost feels (to this humble reviewer) that the developers are splitting hairs between these classes. But none of the powers overlap, so I guess it helps keep things organized. From an uneducated NPC's perspective, however, I'd find it very hard to spot the differences.
And now, the Barbarian. Yes, they still rage; yes, they do massive amounts of damage; and no, their table manners will not get them invited to any formals anytime soon. For some reason, the Barbarian derives his power from a Primal source. The books states something along the lines of "calling a spirit into themselves" or something similar. Frankly, I think this is wrong. A rage is a state of mind, it is almost of form of self-disciplined chaos. A Barbarian's source of power is more in line with a monk or a psion (both classes yet to be mentioned in 4e) than those of a Druid/Shaman/Warden - regardless of their penchant for tattoos and wearing dead animals. Primitive? Yes. Primal? No.
Until we get to the Paragon Paths, that is, then the Barbarian can turn into (wait for it) . . . a Bear-barian! Yes, they can take the form of an anthropomorphic bear to whoop some monster behind! Why? I'm not sure, I guess because they're Primal and all the other Primal classes get to take on animal characteristics - as well as the Shifters. Hmm, I wonder how a Shifter Barbarian feels about being a patchwork Tiger(or Wolf)/Human/Bear - that's gotta mess with your mind. Or a Dragonborn Barbarian . . . But I digress.
So those were my impressions of PHB2 - not necessarily the direction I would've taken things, but I'm not sorry I got it, either.