(for reference, I've used a generic all-comers list with little mech, and my wraith contingent really didn't help me against the dark eldar!)
Crimson Hunter : Brilliant. Simply brilliant. Not only does it make an awesome zoom noise (in my head) but it's vector dancer rule allows it to pirouette above the board, sneaking line-of-sight to that flyer your opponent has spent the last five minutes carefully positioning so it couldn't be shot. It's re-rolls to penetrate flyers makes it super-killy too.
The downside is that it's so typically, well, Eldar. AV10 and no form of shielding doesn't make it very survivable, however having killed the enemy flyers you should be safe-ish (unless you are facing necron spam obviously, cos then you may as well give up).
Warp Spiders : I used to take WS cos they looked cool. Now I take them cos they are awesome! The extra point of strength and occasional AP1 really helps take down vehicles and infantry. Never leave home without some!
On the downside, the warp jump is pointless. for an average extra 1.5" of movement, you might kill one of your own models (randomly determined, so bye-bye expensive exarch!), which seems a bit Orky to me. Be safe people,
Farseer : A useful Farseer is like a dog that can speak...very rare! The randomness of powers, lack of army-wide benefits and frankly pathetic offensive ability, coupled with crap survivability (compared to the characters of other races) has left me feeling very deflated with these chaps. The loss of real psychic defence has also made them less useful.
The chances of me taking one in a serious list are like finding a dog that speaks Norwegian....even rarer!
Swooping Hawks : Much better value for money. The large blast template being AP4 ignores cover means bye-bye reaver jetbikes/imperial guard heavy weapons/tyranids hiding near venomthropes. No longer scattering from deep strike is amazeballs, as is the three shots each. And they're cheaper, 6 of the standard blighters will come in at 96 points, serious anti-horde for your money.
I'm not sold on exarchs though. None of the exarch options seem to add much to what's already there, especially for the points cost.
Autarch : Army-wide benefits for relatively cheap points, winner! making sure your crimson hunter arrives after the enemy flier makes a huge difference, and swooping hawks arriving turn 2 to take out those pesky cover save units can save a lot of heartache.
My only problem is the jack-of-all-trades-ness of the model, leaving it the master of none. I know, I know, for a master of something you need 200 points to spend on a phoenix lord, but it still seems a slight let-down when your Autarch ends up facing an enemy HQ of comparable points value. I also still have no idea what the best loadout of Autarch is for my army. Answers on a postcard?
Wraithlord : Erm, unsure on the medium-sized ghost warrior. He draws lots of enemy fire, and therefore dies very quickly. Serious firepower on this lad just creates a point-sink, and with no way to purchase an invulnerable save (that all other wraith constructs have access to grrrr) AP2/3 weapons soon put paid to him (and there's lots available).
Still one of the coolest models around, especially when given a big sword, I'll probably soldier on with him cos I like the model, in non-competitive game anyway.
Wraithblades : I've opted for the axe/forceshield option with mine for the survivability (and AP2) but there is a serious lack of offense from them. Against any half-arsed combat unit you'll get 5 attacks from five models, and will probably kill 1-2 enemies per combat phase. Even with toughness 6 you won't have enough models with only 5 to seriously act as a tarpit. I might have to experiment throwing an Autarch in with them to add some attacks.
And I'd like to point out how they very carefully have been made to be worse than terminators. For an extra 8 points you get deep strike, 2+ instead of 3+ armour, 3+ invulnerable instead of 4+, 2 attacks each base instead of 1, and S8 instead of S7. Wraithblades cannot instant death a muhreen character as they can only reach S7. In a fair fight, thunder hammer/storm shield termies will beat wraithblades into a powdery smear.
Cool models though.
And the rest I'll cover at some point. I will say though that a phoenix lord is looking like a good choice at the moment, for eternal warrior and 2+ if nothing else. I plan to experiment with Fuegan (who looks like a right meathead) and Baharroth (now gets a 4+ invulnerable save) for eliminating enemy characters and denying the bonus point for slay the warlord........