I rented it (I use GameFly a lot) and I didn't really enjoy it until you get off the "tutorial island" and into the bulk of the game. That's when things really opened up and it became more of the RPG I wanted it to be. Visuals impress me, as does the voice overs. You are spot-on with the Dragon Age: Origins reference, and I'll also throw Elex out there as another reference. I played about ten hours of Greedfall on my old Sony TV before sending it back due to Borderlands 3's release, knowing it would take up quite a bit of my time.
I have added it back into my rental queue in hopes to play some more of it now that I'm in a lull between game releases. I also, like you, have a shiny new OLED I want to play this on. I've spent the last 10 days going back through lots of the games I own and have been re-experiencing them on OLED. Top marks go to God of War, Ratchet & Clank, Rise of the Tomb Raider, and Star Wars Battlefront II. My fiance saw me play the very beginning of Battlefront II's story campaign mission and said it looked so real.
I'm definitely looking forward to more of Greedfall. If anyone is looking for something similar but more on the sci-fi side of things, check out Elex. It's not an easy game, especially early on, but if you stick with it you'll be rewarded with great world exploration, story, and character development.