The Carnifex was indeed undercost in the previous version. It was literally a mobile firing platform with 3A and a S8 Large Blast weapon that has a good chance to instant kill most of stuff while shooting and instant kill them in CC as well. It got a slight “set back” in the new version, increasing its points by nearly 40% (160 pts now) and lost the ability to spam it in EL slots. Though there are quite few cry babies out there, let’s look at it in detail and why I personally do not think Carnifex is any less threatening than before.
Shooty Fex – Shooty fex is very expensive to field now, especially with Tyranofex at slightly more expensive cost but come with 2 S10 AP4 shots. Players will probably not run any shooty fexes. But consider this, you can put the fex in a pod now, you can shoot at what ever you want point blank when the pod becomes available instead of trying to hug every piece of cover save while trying to avoid getting shot at. Another alternative is simply forget about how expensive they are and give them the best upgrades you get. Who cares if the unit is 700pts? It will be 700 pts that your opponent MUST shoot at each turn unless he wants to get assaulted by these beasts. You just have to be able to field some other units that your opponenet must not ignore – a Trigon for example.
Combat Fex – I think this is where the money is at for these babies. A lot of folks prefer Trigon because it has fleet and so much better than a fex stats wise. But have you ever played CSM and tried to pen the armor of Land Raider moving fast? I have, and despite getting 2 dice for being MC, getting a 8+ on them after getting a 6 first is not as easily as it sounds. Now a Carnifex only need a single hit in then it only needs 5+ to have any kind of implication on it. The fex also come with a pair of Scything Talons, which gives you another chance to get some “6″ against a vehicle that has moved fast. Run 3 of them and see what your opponent will do (aside from calling you a dick). Better yet, if you got the models, run 2 pair of them at 3 each! Who cares if they only move 6″ a turn and run another D6. If you have other threats on board, your opponent will either ignore them (mistake) or spent too much time on them.

I’m pretty sure running two units of two will tandem well with a Trygon Prime and some Tervigons on the board. MC overload.
It’s comments like this that I group you with the Type II.