Since the release of the Legion pre-patch, I have played less than 4 hours total. That is not because of some particular dislike of the changes or anything. I have just been outside enjoying the sun, and catching Pokémons!

Since I have played Legion Beta, I had already decided that my hunters were abandoning MM, and will be BM from now on. MM was kind of OP anyway and had a nerf coming.
As for hunters in general, like all other classes many abilities have been pruned. The things I will miss the most is the talents/glyphs for increased pet healing, general pet tankiness, and of course the traps.
In Legion, it doesn't look like it will be possible to do this kind of x5 dps thing I've been doing in WoD anyway, even if we had all previous abilities. The overall boss HP pools, and lack of a Maalus or similar, makes it just impossible to burst a boss, which is often crucial.
Anyway, here is me right after speccing BM. I was expecting much more wipes, and a lot of more time learning this new spec before (or if I ever) would complete the hardest mythic dungeon again.

However with the flat nerf on the bosses, my hunters could even kill Ragewing on the second attempt. I was not even serious about that attempt, when I had fully understood that my pets are not even hitting the boss, I was more thinking of wiping and quitting (or setting up MM again). 2 of my hunters also died in start due to a unlucky (non) spread on the dragons fire spits. Somehow I could turn that fight and kill Ragewing. Even with the nerf that was quite surprising.
Seeing how well this went, even as I still was learning the new spec, I would have wanted to try this without the nerf for a good challenge.