.... My main issue with open world they created is lack of random events and replayability. Everything always on its places, so second walkthrough nothing can surprise you (except different choices in quests).
Actually, I haven't played a lot of open world games before (some GTAs and ACs), but I immensely enjoy this one. Seriously, I feel like I couldn't go back to TW2 anymore (I wanted to play it through one last time). CDPR has absolutely nailed it, never have I felt in my 20 hours with the game that the narrative suffers because of the open world. All the different elements of the game just fit together so nicely.
About the main story:
I haven't done a lot of it, I did most of the Bloody Baron questline (which is brilliant so far), and I met Triss for the first time in the game. So far, it's not underwhelming at all for me.