My thoughts about MCH, as I've been leveling it lately, and just freshly got Level 76 with it the other day:

1). The animations I actually very much enjoy. I'm an ex-WoW player and having my character stand there performing the same 1-2 animations and barely moving is boring. 4.x MCH was boring animation-wise. Animation quality in FFXIV is one of the things that makes combat look and feel cool. Please don't take my backflips and things away from me, I love them. As far as "new recruits expected to backflip" um... no? Because you don't do those backflips and such until you're in the high 50s, early 60s. The non-heated versions of these abilities have you using the older animations. They start out basic with you just standing and shooting and then they progressively get more fancy as you get more skilled with a gun.

2). They merely re-used icons and names of skills as far as the Heated moves go. They could perhaps rename the heated versions of the skills, maybe like Trick Slug Shot or something I dunno.

Now onto things that actually matter:

The only beef I have with the class, is the annoyingly small window when you overheat your gun and you have to dump as many Gauss Rounds (I think that's the name of it?) or Auto Crossbows as you can during this time. It's a very small window and it's very heavily dependent upon input lag, and network lag, especially with Gauss Rounds, and before you get that trait that lets you hold 3 charges of those other two skills that Gauss Rounds helps complete faster, it's very annoying to have to weave those two in-between spamming the two oGCD attacks and being half a second off can hurt your DPS and half a second is easily within what lag can do to you or needing to stop and run out of an AoE or something.

Second, I would argue I would remove the 'stand still' requirement for Flamethrower, again, it stinks to have to move because of an AoE right after starting to use Flamethrower and it seems lots of trash packs have AoEs nowadays and it's hard to actually time a Flamethrower cast and get the whole thing out without having to move).

And last, I can't really say I'm a fan of Wildfire, either. Seems like every time I go to use Wildfire, something stupid happens like an AoE I have to get out of, a gaze attack that forces me to stop doing DPS, etc. Then Wildfire goes from doing decent damage down to doing almost nothing because SE expects you to have 10 uninterrupted seconds to line up all of your best DPS skills before using Wildfire and it just seems annoying to make that happen.

All-in-all, I think the class is 1000x better than it was in 4.x but yet there's still annoying little things with it that would prevent me from using it in any max-level content. It's fun to levelup and tick it off the list of things to do in the game but once it's 80 I doubt I will use it much because of how annoying the above three issues (mainly #1 and #3) are to work around.

SE needs to remember that people do get lag now and then and that the game wants you to dodge things every 3 seconds in some fights.

MCH and NIN make me roll my eyes when WoW players whine about the combat being "Too Slow" in FFXIV, because they know nothing about late-game and they see early-game when most jobs only have 1-2 abilities to use, lol.

EDIT: (2020 and we still have the worst forum restrictions I've ever seen on the internet, that everybody circumvents anyhow)