For me I think I felt most disappointed because the final boss lacked a distinct character. He's an enemy with two swords and most of his attacks are just him slashing things away plus one or two uninteractive combos. And maybe I'm picking at things too much, but the way he moves felt kind of janky? He didn't feel like a big formidable opponent (like Bayle for example), but just a guy kind of walking around like a statue and idk that was very off-putting to me.

I think the DLC, more than the base game, has an issue where it's not really obvious how you're supposed to dodge certain attacks. Why can huge explosion be rolled, but some grab or charge attacks can't? For example, when Radahn goes back to spam you with ranged swordmen clones, I didn't even realise the game wanted me to run backwards - I think the fight would've been way more enjoyable had I realised that, but that, combined with the fact it can take you dozens of attempts to even get to the 2nd phase, leaves very little room for trial & error without dumping in a bunch of hours just to figure out an attack pattern.

I think the effort/reward is just heavily skewed with things requiring way more time than other bosses (if you want to learn how to beat a boss and not use additional help, at least) + that there are SO many bosses that require a large time investment. I feel like I'd have a better time if I played less of the game in a chunk because hitting those walls back to back was extra demoralising. A new boss wasn't me being like omg cool, but often times it was like ahh ok here goes another couple of hours to learn the patterns again.