These are cool models and have neat rules but they are really gimmicky. With only a T3, 4+ save and 12" range, one-shot guns they will die quickly even with their 5+ invulnerable save. They are also extremely expensive if you want any use out of them and make use of the weird combined beam thing (around 200 points) for which you only get one solid shot that is only slightly stronger than a Fire Prism blast. I think they were intended as a heavy infantry hunter as their jetpacks let them run around slow units like terminators but they just don't have enough shots to do enough damage. Taking up an already crowded Heavy Support slot I don't think we will see many of these.
Now we get to my favourite new unit, the Warp Hunter. I don't like the model that much but the rules are amazing. Like all D-weaponry it can cause instant death, wound everything on a 2+, kill tanks easily and is AP2 so ignores all armour saves. The only reason why I don't use Wraithguard is because of their short range but the Warp Hunter doesn't have that problem. Even better, it has the ability to use a D-cannon-like flamer, yes an AP2 flamer that wounds on a 2+. Truly amazing. The gun is even barrage so can fire indirectly. The only problem I have with this tank is that it is 10 points more than any other Eldar tank but that is really a small price for such an awesome tank.
In short I love the new units and can't wait until they release the next Imperial armour, the Doom of Mymeara.