Very good
Still has the base game's problems like the lack of detail and stuff like that, but the new skills, movesets and fights really make it way more fun. Fights like Amatsu and Primordial Malzeno are some of the best fights on the franchise imo, and skills like Bloodlust, Berserk, Heaven-Sent, Dereliction, etc. really change how you build your sets and change the game. The power creep is way too strong, just like iceborne, but there's a huge variety with what you can do.
The story is quite good (to compensate for Rise's), for MH standards of course. The war of attrition between Malzeno and Gaismagorm is really cool and holy shit that quest before Gaismagorm is easily the best quest story-wise in the entire series.
The Afflicted Investigations are a fun system with a few problems. They are way too grindy, it takes way too much to get fun quests (you start up with the lower tier monsters), the monsters are always in their 'delirious' state (but that's an issue with normal rise) and they're a pain to look at sometimes.
The Qurio Augmenting system is way too RNG for my liking. What you get on a charm (I've hated that system since base Rise) or on your armor can make or break your intended set, and the final result is completely out of your control.
Going back on that 'always enraged' issue, I've got to say that this is one of the most annoying things in the game. Rajang being gold stops being special if it's always on that state (really, I've had moments where I got it out of its gold mode, and it went right back into that mode literally 3 seconds after).
Another annoying thing is that the system to join a quest is horrible. Joining someone's quest or getting someone to join yours is harder than most of the fights (when they're not eating your whole health bar just for breathing the wrong way).
Inflation is a bitch, even in the world of Monster Hunter we're not safe from it. Everything robs your wallet and takes your kids. Crafting weapons, upgrading armor or the large number of paid layered armors and weapons that are better than the free ones (thank you capcom, very cool). It also affects the numbers in the fight. Monsters have a shit ton of health and deal way too much damage, and to compensate that, the hunters also started dealing insane amounts of damage and now have way more levels on their armor, but then monsters need to have more health and damage to keep up, but then... oh this is a cycle.
I shit talk a lot but I have a lot of fun, even after losing an account with 200+ hours, I started a new account, passing through the horrible early game to get to the part that i.. dislike less. Jokes aside, very good expansion, some faults but I can overlook those since the rest is just way too good.

Very good expansion, a lot of new moves and some really cool fights, a shame that it adds a small amount to the cast (really the lack of deviljhos is really strange) and part of that amount is fucking magma almudron. That piece of shit can go suck a dick or two.

The Apex monsters are completely out. The system was really badly implemented in base rise but it's still a weird decision, it was a bummer losing some of them. I don't know how they will substitute them. (EDIT 2: uhh well..)

The endgame is certainly decent (EDIT 2: fucking no KEKW), at least it's not as bad as rise's (it didn't even have one), but it's at the early game that you notice how small the new roster is. The majority of key quests are base game monsters, and some of them are even more annoying, like arzuros.

The lack of detail still hurts, the world just isn't the same as world's (HAHA GET IT "WORLD" I'M SO FUCKING FUNNY), I guess we can blame the switch for this. On top of that, I still don't like the wyvern ride mechanic, every monster encounter outside of the quest target's is scripted to a fault, leading to monsters like bazelgeuse losing all their personality. The monsters' AI is terrible, it's always enraged (it's even worse with the afflicted, god bless that PoS of an endgame), the input reading system is still a bitch to charge blade players (among a series of problems that plagues CB in this game), rathian's tail flip still poisons you even with a cut tail, khezu hasn't been deleted from the game, almudron still sucks, a lot of things from rise that could have been changed in sunbreak. At least they improved the wall running.

I complained for the majority of this review but I end up having fun playing this damned game. I just hope that the title updates add a shit ton of monsters and cool events. (EDIT 2: hahhahahahHAAHAHAHAHA)

Edit 1: The near genshin level of RNG that the armor augmenting system will bring in the first title update might make me lower this game's score actually

Edit 2: They're pushing the paid dlc way too hard, time to lower the score

Edit 3: Now that we know all the game's monsters, I can say that the roster is excellent, but the power creep is terrible and the monsters spend more time enraged than non-enraged