Supposedly Take Two forced Gearbox to rush the DLC under threat of funding cuts.
I don't think I can list all of the bugs (because the list is 3x longer than the patch notes), the game is essentially unplayable for most people- including Russians who got rug pulled on the day of release by having the entire game region locked without warning.
Regional pricing is also marking up the DLC as more expensive than the game itself. Regional pricing was very quickly fixed.
Now the game is getting review bombed and lots of people are just refunding &/or down patching since the game is broken even without buying the DLC.
Kinda bummed about this. Even the original coder for the game came out and admitted they butchered it.
A lot of the things are shockingly strange, like how a ton of things (including sounds???) were suddenly tied to FPS in the latest patch. I've played the DLC for a bit (obliterated with all 3 new characters to get the skins) and with FPS max set to 60, haven't had too many bugs (AI breaking and things falling through the floor, mainly). No immortal bosses, and definitely not the worse stuff like wiping all your save data if you plug in two controllers on Xbox.
Even without bugs, I'd say the DLC is a letdown. It's like it was made by someone who'd never played RoR2 before. Multiple items based on being hit, in a game where being hit usually means instant death in the later stages, and another based on being below 50%HP. Maybe it has some weirdo bonus with some of the lunars (Shaped Glass or Tranquility) but this is a fucking white item that's just diluting the pool. The new boss is bad, and the characters are all over the place. Seeker is pretty solidly fun but seems a bit OP with a self-resurrect and on-demand heals. Lost Son is... fine, but his melee sucks and the idea of "slow character with lots of HP" just isn't a thing you can do in RoR. Lastly the Chef is just awful. None of his kit synergizes and his passive heal (his main thing!) seems to be equivalent to maybe 2 Monster Tooths.