I play PvP mostly (I'm sure I'll PvE when Factions comes out) so my evaluation will be in terms of what I tried in PvP:
Monk:
Boon Sig- this is really nice nrg management skill for boon prots. What I love about it is that if used correctly it can keep up with you nrg needs much moreso than P&H has while still giving you the benefit of being a Monk nrg management elite (allows you to spend more points on Prot). I'm talking Boon Prots here.
A side comment: the addition of many new and useful sigs will create the need for Sig control (much like corpse control) in large teams. I think this is wonderful and a nice strategic move.
Necromancer:
Blood Drinker- This skill is weird, I was thinking that it can be used along with Plague Sending/Touch and Virulence but didn't get a chance to use it a lot. It has a great damage output for the nrg cost and a relatively low cooldown.
Cultist Fervor- Wow, wow, and wow. This skill despite the high life sac works very well with Unholy Feast and Oppresive Gaze (large team obviously) but more importantly I used it on a Heal Party monk for alliance battles- it was hillarious I could literally spam HP without ever running low on nrg and negating the sac damage completely. Wonderful.
Jaundiced Gaze- This skill is a cross-bread between Dark Pact and Vamp Gaze. I played with it a bit but it will take more practice than a few runs to get the sac to work with the health gain. I liked the idea of it tho.
Oppressive Gaze- This is a weaker version of FoC with a different condition to trigger the health stealing effect- you need to have your targets weakened instead of hexed. Obviously Enfeebling Blood + Opp Gaze will be a common combo. The skill is very powerful in large teams.
Vampiric Swarm- I was very hyped up about this skill but I found it kind of awkward. Perhaps it will take me some time to get used to but the 10 sec recharge gets to you. It doesn't come cheap either. But then in large teams, it might me something to consider spamming along with Unholy Feast and Cultist Fervor.
Order of Apostasy- This is the ultimate chant killer. Amazing skill. Despite its high cost it worked just fine for me (I combined it with Heal Area and just stood way behind and out of fire). BUT and this is a big BUT, OoA has made IWAY strong and well again. And this is a MAJOR concern. I don't think the skill is broke per se. I just think that there is a little bit needed to push IWAY over the top always and this is it for Factions.
Reckless Haste- Let me tell you- I haven't had so much fun with Spites in a long, looong while. Spites + RH is a killer, hillarious on assassins. Cover it up with Parasitic Bonds-> you will get your health very, veery soon
Soul Bind- I was actually very excited about this skill. I tried to combine it with Faintheartedness and Parasitic Bond and just hit with Wastrel's to trigger the effect. I didn't quite get it to work tho... like I didn't find it all that useful... Could be just lack of xp but... I think this skill needs a review of the KD trigger. Whats the point of nailing attacking things, if I can't interrupt their Heal Sigs and Troll Unguent or whatever the case might be?
Well of Weariness- Big fan of e-denial here. This skill was awesome- not only is it a nice e-denial addition (it's like making everyone in the area maintain a chant) but it's cheap and works for corpse control perfectly well. Used it on my mesmer mostly tho.
Animate Flesh Golemn- WOOOOOOOOOOOOOOOOOT. This skill RAWKS. I don't think anyone will disagree in here. Soooo much fun to have the big daddies of the undead on the MM's side. Lets get it ON!
Animate Vampiric Horror- I was so-so impressed by this skill. Horrors don't do enough damage to really say I felt a significant benefit from using them. I'd rather combo my tank Golemn with Fiends. In PvE maybe Vamp Horrors will be much more useful. Or... another option is to combo Cultist Fervor with both horrors and fiends but... who would wanna miss on the Golemn!!!
Bitter Chill- This skill is really nice if you do an AotL MM. It's a nice and cheap skill to use for initial damage.
While I'm at it, I wish I had tried Discord... looks like an awesome monk killer skill.
Mesmer:
Overload- It is my understanding that this is like an anti-ele type of skill. It's ok... but it's also nothing to be excited about.
Unnatural Sig- The return of this skill is a big one. I love it. It's nice for killing annoying Rt spirits, it's nice as a finishing spike (Mesmers always seem to need the last move), and I can finally make a highly effective and damaging Sig mes.
Accumulated Pain- Phantom Pain/Shatter Del alternative. I used it on top on Images of Remorse and Conjure Phantasm-> 10 degen, some minor spike damage, and a Deep Wound. Worked perfectly fine.
Conjure Nightmare- This skill is damn costly... I used it with Glyph of Energy. It is cool, because of its low cooldown you can spread it around and max degen a lot fo things and if u use GoE or smth similar to negate the cost, it can be really useful.
Images of Remorse- Wonderful, wonderful, wonderful new addition. Clumsiness meets Conjure Phantasm for a cheap, low recharge anti-war, ranger, assassin move. If your target isn't attacking- who cares- give them some cheap 5 degen anyway!
I didn't try of the new mesmer elites. Though I'd use my faction unlocking other stuff instead. Speaking of which... these elites... they are sooo situational. The ones that I was thinking about trying were Psychotic Instability, Stolen Speed, Lyssa's Aura, and Power Leech. The rest didn't impress me enough. This goes for most any char I played btw. You see like 4-5 interesting elites and the rest are kind of the new "nice to have", "never to be used" elites. (reminds me of Fevered Dreams before they buffed it)
Well, I typed a lot. I'm yielding the floor to others. Curious to see what the rest of you guys discovered.