How'd you feel about Nameless King?
I felt like bringing friends to even the odds! Even then you better pick guys who know what they're doing, wearing Dragonslayer Armor and shit, or he'll just as easily kill everyone.
Honestly the prospect of running and dodging a flying enemy who can spout flame made me stop playing and it's been rough finding time to get back into the game.
Same! Other than the final boss (and messing up 80% of the NPC quests) the only thing left is the Nameless King but I really wanted to do my first play through solo,but that fight is impossible. I put the game down after like 60 hours straight and can't seem to find the energy to pick it back up and finish the damn thing.
And that's why, once I satisfy my compulsion to finish the game ASAP (the goal of playing any game in my mind, especially if there's an interesting plot), I can relax and enjoy mastering its subtleties if I wish without getting frustrated or burning out on it (I hate getting bogged down, which just exacerbates the difficulty).
I honestly didn't find him too bad solo though; the dragon part is manageable if you don't lock on and avoid the vertical flame breath, and once he's grounded I could dodge his shit and hit him back regularly without especially more difficulty than other tough enemies. He's just overpowered so you don't get to make a mistake, at least more than once (I hear the Dragonslayer Shield REALLY helps though). Talking to you guys, I kind of regret not finishing him by myself now; I was drinking a bottle of Italian wine and decided he just needed to die!
As for what I think of him outside the fight, it's a very cool idea and is executed well. That whole area feels like an included DLC for fans, and he truly lives up to his reputation and the closes the loop on that last bit of DS1 lore; which really made the first game for me (no matter how much I enjoy the nuanced mechanics and balance of DS2, the plot is so generic by comparison, I'm happy they returned to the well in DS3).
Anyway, have you guys tried fighting him as summons to get in some practice against his moves without the same pressure to win, or not lose? Plus, actually seeing him go down a few times can't hurt. I think that's half the battle, and if you don't plan to NG+ (or suspect it won't really happen =) it's a good way to experience all the bosses in groups and solo. I wish I could have experienced more group play on DS1 but nobody was on the server when I was playing. I literally beat the game the day before the global restart day.¯\_(ツ)_/¯
Update: VICTORY ACHIEVED. I wish the
Firelink Greatsword had the Claymore (my DS1 favorite) move set instead of the Bastard Sword's though.

Will still be fun to cosplay as the
Soul of Cinder but I may go with a +5 Sunlight Straight Sword with Carthus Flame instead. The great swords are just too fucking slow for the almost negligible increase in AR, which the SSS weapon art totally negates (technically I could use any weapon once I cast the buff, but not conveniently). Lorian's ultra greatsword has potential though! Anyway, once my enthusiasm for the weapon upgrades subside I may take a break for a while.