I will be to the point here, he is a very powerful unit in the right right situation and as we have seen he can curb stomp just about anything in reach, so he is very effective. However this does mean that he has to be used in a very limited way, closing in with high value heroes like nagash and archaon before beating the pulp out of them. So in essence to get the most out of gotrek you need to kill a hero of points higher in value than he is.
So this is great, but then we also have to consider other factors. For one he may be able to in comparison beat 2 carnosaurs, but two carnosaurs have much more flexibility to offer than he does, especially in speed. Are carnosaurs objectively better? No, but Gotrek is limited in his hunter niche.
So to actually kill something he needs to close, and this arguably is the difficult part. Almost all heroes are faster than him and he will have to pass through terrain and chaff. The way AoS has evolved, winning is not done just by killing. Of an expensive model is tied down for long enough to reduce its effectiveness, that is all that needs to take place. This can be argued that if Gotrek limits a huge heroes zones then he has arguably fulfilled his purpose, but he still cost a huge amount of points to just zone out the enemy, so not really a win. Furthermore he can easily be tied down by chaff, from skinks to skeletons and other cheap crap. A turn or two will significantly reduce his effectiveness. So overall, he is hyper lethal, but he is limited in his niche ability. If he can engage, excellent but arguably a cheaper model like a Star drake would be more flexible and more viable. If he looks cool and you want to use him, then do it! After all cool stuff is a big part of the fun
