What's the deal with Dead Cells? I played the base game only 2 or so years ago and it wasn't particularly impressive. Mechanics are ok. Level design is ok. Soundtrack is ok. Art style ok. everything just ok. I don't get the hype. There's numerous better action-roguelikes or metroidvanias out there.
Seems like you didn't play it much from that description.
The levels are procedurally generated and only have level design in the "LEGO brick" sense, i.e. not at all. This of course instantly disqualifies it from being considered a Metroidvania, and only retards and journos will call it such if they've played for more than a few hours. I am normally not a fan of procedural generation, but Dead Cells makes it work by nailing other elements of roguelite design -more on that later.
The mechanics of the game are actually pretty good, verging on great, and there are some really fun under-the-hood interactions between different items/powers/mutations/stat builds, but the nature of the game's progression system definitely slow-rolls this side of itself, and the average player is unlikely to see any of these interactions until somewhere around the 30 hour mark (although to be fair I have 350 hours played, so that's a relatively small fraction of the play experience for some). Grind is overall the biggest problem the game has, and the devs don't seem interested in addressing that (which is unfortunate).
Soundtrack? Eh... can't really comment. I rarely listen to games without my own music on in the background. From what I can recall: yeah, Dead Cell's is serviceable, but nothing special.
I think the art is pretty good though, especially in some of the more horror themed biomes. If the art design doesn't do it for you then I can see why it would be meh, but they're
very consistent in executing on the style they're going for, and for me it works.
Curious which action roguelites/likes you think are obviously superior to Dead Cells. I've played a lot of them, and the only one I would say is superior is Hades, and that's coming very close to comparing apples to oranges.
Things I think you might be missing about Dead Cells:
Content. Dead Cells has an insane amount of content, especially with the DLCs. I don't know of any other modern roguelites that offer such a breadth of content, nor any other roguelite that has allowed it's content to influence build-choice for any given run (e.g. in a run that you're being showered with survival gear and stat boosts you are probably going to want to prioritize biomes with slow-moving, but heavy-hitting mobs who are easily parryable for optimal success).
Platforming controls. The only (relatively) recent game I've played that I think beats Dead Cells here is Hollow Knight. Dead Cells has
very tight platforming controls (though if you didn't play to the point where you get the Spider Rune this may not be all that apparent).
Fairness. Dead Cells is a pretty hard game, especially once you're in BSC3 and above. But almost every time I die in it I think "FUCK... well, ok... I guess that was my fault." Either I built my char stupidly, or I got greedy and took on a challenge that I knew was going to be very high-risk for my build/loadout, or I just cannonballed off a high-dive and landed in a pool of spikes because I wanted my time bonus for the level (this is where that intelligent procgen level design comes in). It's very rare that I throw down my controller in a fit because the game blindsided me with some stupid bullshit.
I think you would probably like it if you gave it another shake, though I would say that (unfortunately) the DLC is probably mandatory for maximum enjoyment as they have added a lot of fun items/powers/biomes and also the best bosses (only taking about RotG, Bad Seed, Fatal Flaw, and Queen and the Sea; haven't played the Castlevania one yet).