I got in my first game last night, and I'm not really counting it as such because it was a team game (DA and IG vs. IG, Daemons and Nids, we had an odd number of players). Still, here's what I found out:
Tervigons rock. I had mine in reserve, so they didn't start pumping out gaunts until turn 3, but by turn 5, I had summoned 47 Termagants. One of them even shut down on the first turn I used it. That's over two hundred free points of Termagants, and had we continued the number would have been even higher.
Regeneration is great on your 6-wound creatures. My Trygon got in a fight with Azrael, and while they fought for 3 turns with neither the victor (the game ended before we could see the end of the duel) the Trygon probably would have died without it. The Guard player told me he didn't want to shoot my Tervigons because they would have simply regenerated.
Biovores are decent, but I think they need to be taken in full squads to be most effective. Don't forget to put that spore mine down if you miss by enough! I forgot twice and while it wasn't a game breaker I was missing half the fun of biovores.
Zoanthropes are great, but psychic defenses suck, especially the old psychic hoods. My opponents had one psychic hood but he didn't show up until late game, so I got to attack uncontested for a bit. While I rolled poorly on the vehicle damage charts, I still did enough with only two Zoanthropes to draw lots of fire. That 3++ comes in handy now, until they start bringing out psycannons. Which they did.
Mycetic spores are great. Being able to deep strike with impunity is a power trip. I put a barbed strangler on mine and managed to kill a few guardsmen. The funny thing is that they never bothered to shoot it, even though it was an easy kill point. There were so many other high priority targets that the thing just kept shooting and shooting. I may not take the gun in future games, but I had some points to spare.
Next game I hope to try out a few more new units, then I'll probably settle on a list and focus on that.