I've yet to beat Orphan of Kos yet, as I find the entire Fishing Hamlet to be a massive jump in difficulty from the rest of the DLC. The duel in the Astral Clocktower feels like a conclusion itself, and I think that's what they meant when they said they combined 2 DLC into one with this. I could see the current DLC ending there, and then Fishing Hamlet being added later with an entrance over at Byrgenwerth or something. (And maybe one or two bosses added)
The addition of actual NPC stories is great, and I love the new weapons and spells. I'm running an Arcane Build with Kirkhammer and the new Moonlight Sword. I love the new shield, it compliments my regular Shotgun well. The new spells that are basically a Great Fireball and Soul Arrow really round out the Arcane Build and makes it very viable. The fact that you can have both of those spells at your fingertips WHILE using a shield and an (untransformed) moonlight greatsword gives you SO much versatility. I have soul arrow on my SQUARE attack, and the Dark Fireball on the first slot of my Touchpad menu, with a few extra spells on my Square slots so I can swap to them when needed. It basically means I can pull out a range of abilities and fight from range while not needing to drop my shield and basically overpower enemies that gave me trouble before.
I'm running the chalice dungeons before I try again to fight Orphan of Kos again and the additions to my arsenal, as well as the addition of NPC's to the chalice dungeons REALLY help break up what used to be a huge slog of monotony. I basically blasted my way through Pthumeru 3 and the new spells, shield, and sword are making Ailing Loran a breeze. I can fight spiders at a distance and fight while backing down when too many strong enemies are following me, or I can ambush them from a safe distance. It feels like it really rounds out my playstyle and allows me to have actual fun with the chalice content.
My current playthrough is basically doing the main game up to mergo's loft, with pthumeru 1 and 2, and both hintertombs before Rom, and then after mergo's wet nurse I do the dlc up until after Maria, then I do the rest of the chalices, then Orphan of Kos, then I go to the final bosses. Because of the new gear from the DLC, I don't need to power level to beat the chalices. I can back off and still put on an offensive, and the npc summons help out in troubled floors. It feels much more fast paced and way less tedious.