Otherwise, I like the chaos book so far, though it made my particular collection a little tough to work with, but thems the breaks. I've really enjoyed playing a lvl3 tzeentch terminator sorceror with some tzeentch terminators to back up Abaddon. After the obligatory tzeentch power (preferably gift or doombolt), I usually start rolling on the telepathy chart. Either hypnosis or invisibility is my goal, but psychic shriek and the one that takes away fearless are not shabby either. I'm still using my old cults as troops, with 3 squads of chosen and one of thousand sons, along with some autocannon havocs and obliterators. Against balanced marine lists so far I have done extremely well, but I still haven't played Grey Knights with Abby yet, and I anticipate they would be tougher. Against xenos... I think I have lost one or two times, can't recall right this second. Mostly I have been creating a rhino corral and slowly advancing in the desired direction. In my experiences, Abby's 12" preferred enemy rule greatly enhances the obliterators and havocs at range, and all the other guys close-in. The rhinos are really for an assault speed bump, deep strike buffer, and portable cover more than mobility, but in a game where they're likely to get shot up first turn, I'll keep most of them empty so my troops don't get stunned into inaction when their cars do. Thousand sons practically beg to walk'n'spray anyway, and the khorne guys love to get in and start taking skulls rather than take 2 turns to get into a scrum - though since they have bolters, they do all right jumping out from a rhino than other assault troops. I actually like Chosen quite a bit with their full equipment loadout. With everyone walking, they can put out more long range bolter shots anyway. But like I said, most of my luck has been against balanced marine lists, and overall I would consider this mostly a "fun" army given its limited numbers and flyer defense.
I also started incorporating the aforementioned telepathy superstars into my Saim Hann build by including a second farseer to fly around with the seer council. Invisible fortuned jetbikes are the shit. Plus they have embolden to help reroll failed leadership tests, so getting the powers off is pretty likely. Also I've noticed fire prisms got a nice boost from the new rules for blasts against vehicles. The jetbike/skimmer eldar are not too shabby overall but can have trouble putting out damage if they take some key losses early.
Necrons would probably be my most competitive army right now, just based on their decent survivability and trick plays. The douche canoes seek out trouble better than a teen actor, so I typically use them to destroy or entangle the more devastating portions of an enemy force, while everything else hacks away at infantry and other scoring units. Obviously I can't complain about Night Scythes at all, and they make the double-despair-mark squad a great free safety against any death star unit trying to ruin my day.
My Berzerker/Blood Angels have done ok. Longer charge ranges can only help these guys, given that I use mostly jump or bike infantry. You have to be more careful with a blood claw dreadnought; terminators will now stop these guys cold. Dante's still a beast and axe-wielding (ex)sanguinary guardsmen are great too. I think the blood angels rules still suit my berzerkers much better and more characterfully than the new chaos rules do, though I do like khorne bikers and raptors in the 6th ed chaos book. I just can't find the points for them.
Guard does just ok; I play