People dislike HBHM for multiple reasons.

1st boss is a complete joke, it's just a glorified trash room with a "hey lets tether the healer to pretend it's a mechanic". There is literally nothing in there that can be considered a boss other than aoe dodging.
3rd boss is the disappointment that it is, the guy was meant to be a legend among the maelstrom and all he does is spam a aoe on phase 1 and a weak poison on phase 2 that is so weak that my medica II completely nulls the mechanic of having to grab a antidote from a box.
2nd boss is actually ok.

But other than the 1st boss, the real issue of the dungeon isn't really the bosses. The real issue is on the trash pulls.



GATES EVERYWHERE with the tiniest possible pulls of every single dungeon ever with damage being dealt being so low that tanks can almost self sustain themselves without a single heal. As a healer main, it got to the point that i'm not a healer anymore on dailies, i'm just a 3rd dps in the group that once in a blue moon throws out a regen, medica II and tetra and I can't even aoe unless the tank pulls a whole section since using holy with less than 4 targets is a huge mp waste.
One thing are mobs hitting so hard that you can't group them together, the other is removing all possible challenging attempts with gates which is what hullbreaker HM and antitower on the previous update did.