Yeah, sorcery and incantations are super OP, and this lack of balance does come as disappointing. Though, as you said, Ashes of War are an excellent addition, because they add even more flexibility to your build. Melee-only users now have the opportunity to use magic skills without having to carry a spell-casting weapon.
Wing of Astel and Moonveil katana cripple bosses within seconds using their Nebula and Transient Moonlight skills, respectively. Couple that with an Ashes summon, and everything becomes trivial. But, at the same time, it remains super fun. The grandeur of some of the boss encounters is on the level of Burnt Ivory King from DkS2, Martyr Logarius from Bloodborne, and the colossi from Shadow of the Colossus.
My favorite bosses are Radahn, Malenia, and, of course, how can I not mention the final boss. One particular instance during that fight had my jaw dropped in awe when I realized what the boss was doing. It doesn't get more epic than this. Phenomenal stuff. From Soft has truly redeemed itself after that boring ass final fight against Isshin Ashina in Sekiro
One of the only real disappointments I have with the game is that leveling up isn't solely dependent on beating bosses. One of the few things I liked about Sekiro was that it had blocked the "grind to win" tactic. But I'm all for accessibility in a large open world game, so no big deal
Speaking of the open world, it's just massive, and almost completely seamless. It's incredible to head towards some random ruins that you see in the distance, only to discover an underground passage there that leads to an entire dungeon. It's similar to Breath of the Wild's shrines, but the element of discovery is better realized here. Also, your steed is the best controlling and most agile four-legged ride in an open world game to date.
Haven't delved into PvE or PvP as yet, but will be dropping in from time to time in order to help or invade others.