The giant lizard thing is the worst boss I've ever had the displeasure of fighting in any videogame, the dickheads in MHGU included.
Even ignoring that bullshit that wasted 10 minutes I'll never get back, the game is janky as all hell. That QTE cutscene that everyone laughs at is not a one-time thing, everything in this game is like that.
Speaking of the quick time events, they are definitely the worst thing about this piece of shit. The giant lizard is hellish to fight, but at least I only have to fight that cunt once. These are annoying, way too fast to react without failing once, and appear constantly, I hate whoever programmed these.
The combat can be fun, simple but not horrible. However, there's not a single boss fight that is fun, they are all horrible, some can be cheesed for 2 minutes straight, while in the others you have to sit there and realize that you're wasting some time of your life playing a shitty game made by Activision.
EDIT: I said that the lizard was the worst fight ever in any game... well don't worry, it is still horrible, but we have another moron in our way.
Remember when I said that the bosses are not fun? Add consecutive quick and more annoying than usual QTEs, and you have the Sandman portion that you play as Goblin.
If you, on top of that, add a shitty fucking gimmick and attacks that are so much buggy that they make Sonic '06 seem like a masterpiece, and you have that Rhino cunt.
Turn all of that up to eleven, and you get the shitshow that is Venom. For real, it is so bad that i genuinely think that it was programmed by an aborted fetus. You might think this is inclusive, but it's just retarded.
I would rather kill myself, get reincarnated as a black american and annoy a police officer just so I would be killed again than touch this piece of shit again, I'm done.

Honestly this games has a lot of errors that old MH is known for, shitty hitboxes on attacks that are large by default, add the fact that they are fast and can, and will, one-shot you.
Health pools larger than your mom and multiplayer scaling that's forced down your throat if you want to reach the """good stuff""" is another problem with the old hub system, thank god it was changed for worl- nvm rise fucked it up again.
Don't get me fucking started with the early game, it was so bad, but so bad, it took me some months to force myself to go through it, I got to Astalos and for some reason I started to think that the game was going to be excellent, big mistake.
Boring quests, shitty monsters that you are forced to fight more than once (examples being, the walking dick, the psychotic chicken, the retarded flashy bird, the dipshit that is the nibelsnarf and every single piscine wyvern in this garbage of a cast) with not that many good ones (examples being Astalos, Glavenus, Valstrax, etc.)
Quality over quantity? The developers of this game never heard of that, so they got every shitty monster under the sun and dumped those morons here. I'm looking at you Lao
I've said all of this seeing that I hate parts of this game with passion, but somehow I still have fun with it. When the fights are good, the combat is fun, lacking the huge QOL changes that came from World, but the styles and hunting arts are incredible.
The multiplayer is really fun (almost) regardless of the monster (it even makes Lao fun, incredible!) and the best fights here are really fuckin' good, I have some traumas from trying to solo Boltreaver with mid level G-rank gear, but it is very fun, easily part of my top 5 favourite hunts in all of monster hunter, even counting Iceborne.
Edit: Turns out yuzu has a large as balls input delay and I really only noticed it when trying to solo boltreaver II recently,gOD DAMN IT I WANT A PC PORT N O W

Extreme Nago is a good example of a boss fight done just like a fetus in the womb would. Someone just kicked the keyboard a bunch of times, called it a day and published the game like that. I don't even want to reach stage 9, that'll be even worse.
Ignoring that trainwreck of a fight, the fact that the balance is a shit-storm, the game has likeable characters (most of them, at least), a fun story, perfect graphics and a OST full of bangers. I can say that I enjoy it overall.
Edit: Jack-o' :)
Edit 2: Bridget :(

This game aged like milk. It's incredible how bad it controls nowadays.
The music is really good, probably the only reason why I didn't give this game an even lower rating.
The level design is literally a hit or miss, you can have a good level, but you can also have an extremely boring and/or unfair one.
The camera is shit, everyone knows this, moving on.
To put it bluntly, the most overrated game I have ever seen.