I'm gonna be totally honest here, I genuinely do not enjoy Caves of Qud that much.
However, I'm still going to give this a thumbs up. This game truly shines when it's your first traditional roguelike or its your first time playing this game period. The sense of discovery and immersion in this game is truly something else, and you're REALLY gonna feel that early on. Not to mention the pure joy of experiencing something wacky and cool for your first time, there is a plethora of that in this game.
My disappointment in this game stems from being a long time roguelike enjoyer, someone who has played just about every traditional roguelike you can possibly think of (DCSS, ToME, Achra, Cogmind, Zorbus, Nethack, Rift Wizard, Demon, you name it). In Qud, I have played and gotten to the end of current content on Classic mode to give it a fair shake. I've tried a few different character builds and have watched a few youtubers, trying to get a sense of the true scope of the game. Ultimately, I do not really see a reason to play Qud over most other roguelikes, for me at least, perhaps you may feel the same way if you're an avid roguelike fan (though chances are you already have this game if so).
The game is not very well balanced, neither for the player nor the enemy. I do understand not everyone is going to care about that, but it is indeed something to consider. Speaking of which, one thing that isn't balanced are the mutations against one another. Roguelikes can often get away with having things be unbalanced under the "Work with what you find, not what you want" premise that is so often common in roguelikes, but the issue with the mutations having clear superior and inferior choices is that they are all available to you at the start of the game. Randomly mutating and getting an amazing mutation in DCSS feels great, but simply picking multiple arms or legs because they are just so strong for what you're trying to accomplish that run, the feeling is completely muted in comparison. And new players are going to get frustrated when they pick and put mutation points into garbage, and when they ask "What went wrong in my run?" you're going to have people in Discord, Reddit, Forums or wherever telling them that X isn't worth grabbing or investing into, that shit is always lame and makes you feel like the game is not as vast or felixible as you originally imagined it to be.
Leading from that, let's talk about build diversity. I've always seen this hailed as one of the game's strong points, and I genuinely have no clue why. There are a grand total of 82 mutations available to you at the character creation screen, and this INCLUDES MORPHOTYPES AND DEFECTS. Excluding those, we have 62 positive mutations, including both the physical and the mental. It's honestly not that impressive of a number when you consider the diversity in character creation/building in other roguelikes, or perhaps even other games in general. Even less still when you take into account that most of the 1 point mutations are literal nothingburgers. Some of the ones that are good can also just be stat boosts, nothing that really changes how you play the game in any way.
Character builds in Qud seem to boil down to 3 different types: melee-dude, gun-dude, and esper. These are basically what I see every single time when I see build suggestions or watch someone else play the game. You might argue "That's not fair! There are other types of melee weapons so you can divide that category." I mean, sure, but to me they all play so similarly that it renders the point moot. Let's consider two different types of melee characters in DCSS for example: a berserker (melee-dude who worships Trog) and a death knight (melee dude who worhips Yred or possibly Kiku). These two characters have wildly different tactics and things to consider. A berserker will want to keep fights in tight-confined spaces because when they go berserk, NOTHING can beat them in a 1 vs 1. A death knight may want to fight more out in the open, because the enemies they kill are giving them zombie allies, and they want the area to be as open as possible so all your zombie allies aren't stuck doing nothing in a tight corridor. To me, there is simply no comparison in qud.
Which brings me to my next point: combat in Qud. My word is it boring, like genuinely so. There are a few interesting things you can do with the gas mutations and a few of the mental ones, but combat in Qud is 95% fighting popcorn mobs that require no thinking whatsoever, and the rest is your standard roguelike flair, essentially luring enemies in corridors/upstairs/off-screen or whatever to fight them one on one or in some advantageous position, nothing too special there. I can get that sort of experience in many other roguelikes, and then some.
Honest question though, why not add in a couple or so mutations every other patch? Is there a reason why it's been AGES since a mutation was last added? Balancing is extremely infrequent, as well, to make the bad ones not feel so bad or the strong ones not feel so mandatory. That can go a LOOONG way in making the game feel more diverse. Why not add a Scales mutation? A Chitin Exoskeleton mutation? A mutation that makes you constantly leak acid? Camouflage mutation? Like, I dunno, the skies the limit! Like cmon guys, you had an update called the "Molting" update, that would have been the perfect opportunity to add something like that! I think a lot of hardcore roguelike fans are going to miss some of the long-term crunchiness that this genre is known for.
This is getting long, but another misc thing I wanted to mention: the procedural generation. It's bad, like doors leading to walls, random wall placements, there is genuinely nothing aesthetically pleasing about most of it, unlike some of the other roguelikes mentioned. There are a couple themed dungeons in Qud that look.. OK, but nothing too great honestly, and those are few and far between, anyways. And the less said about the procedurally generated books/histories, the better.
I don't want to end on a negative note though. My gripes with the game are probably fixable in some capacity, and everything else about the game is fantastic. God I love the general aesthetic of the game, and melee combat honestly feels satisfying. Seeing the tiles move into one another, and sound effects like the axe cleave, whereas most roguelikes its just two static frames lowering each others health bars, sometimes with no sound even. Qud kills it in this regard, the game FEELS really good overall.
For the reasons I mentioned at the beginning and at the end, I have no issue recommending it. If anything I said is a dealbreaker, then you know what not to do, and maybe check something else out instead. If it's not, then what are you waiting for, hop in!