I know this is going to be an unpopular take, and I'm not saying the game is bad, but I don't think that the Soulsborne formula fits all that well with a gigantic open world fantasy game. What's missing for me that I get from other genre staples like Skyrim or The Witcher 3 is a sense that there are people in the game world whose entire existence doesn't revolve solely around trying to kill me at first sight. Where are the bustling towns, the pubs, the quiet farms, the average townsfolk who just go about their daily lives? Now I've only played a few hours of Elden Ring so maybe all that stuff is there eventually, but for now being unable to walk past a single group of individuals without them immediately lunging at me in a berserk rage is frankly exhausting.
I loved the game to bits, but I agree with this. The typical Dark Souls storytelling doesn't pull its weight enough here.
In fact, the story and lore here are the poorest they've ever been. I'm not usually a fan of how From does this, but Bloodborne proves they can craft fascinating lore and backstories, and Sekiro proves that they can tell good stores - both without interfering with gameplay. But they failed on that account here. I was just shaking my head saying "huh, okay" during the final cutscene - couldn't care less about what happened. That's a failure. And as you've said it made the "open world" feel more like an "open level" than a real place.
This is the one place From refuses to improve, and it's a shame. You don't need quest logs or relationship charts, just make me care about the characters and the world.
So IMO From completely dropped the ball at the last couple bosses. Way to over tuned. Relentlessly high damaging attacks and little time to heal/attack. Godfrey was taking forever by myself. Used a spirit and killed it in one minute. The actual final boss I am shocked they managed to make something so unfun.
I thought the actual final boss was piss easy, it was just a poor design. Really strange, in concept and execution. Didn't really land. The fight before it was fantastic by comparison. Maybe I was just overlevelled at that point (or maybe dual wield claws with 70 dex are OP, I don't know), but it was all the mid-game bosses that gave me the hardest fights. I went to Rykard after Stormveil and that fight must have taken 40 goes.
EDIT: There's no doubt, though, that they have tried to balance players using multiplayer summons by designing the fights around single players using summons also. There are some late game duos where the game is clearly assuming you'll have a summon, whether it's another player or an ash.