I just finished Rhythym of War last night. I think it's by far the weakest of the series. Though many things happen that will likely have ENORMOUS consequences for the story going forward, I found it almost a slog without a payoff. Oathbringer at least had the payoff of the Battle of Thaylen Field, and I enjoyed the leadup to it starting off when the POV shifted to Szeth for a bit, IIRC. Rhythym of War didn't pay off like that for me at all. I also think that some of the characters that showed up in Oathbringer that were from the larger cosmere could have had more of an appearance or more to do here. Though there were many things learned about the greater cosmere here that were formerly mysterious, the way that was handled was not well done IMO. Sanderson handled it almost more like a matter-of-fact data dump in several cases in this book, and that's out of character for how he handled revealing such information in the past. Granted, he was going to have to increase the rate at which larger cosmere info is revealed from the tiny trickle it was to something more, but this was just done poorly IMO.
I tried to keep this mini-review as spoiler free as I could, I might do a longer write-up later with spoiler tags attached after I have more time to process it all and read some more wiki shit about things I forgot from before.
And as a reference, I'd rank the main Stormlight Books like so: WoR >>>>>>>> WoK>>Oathbringer>>>>>RoW.
Hopefully the coming book about Szeth and Shinovar will be a step up.