I'm also done with BaW. All in all, it took me 170ish hours on Death March, with everything that I know of completed.
BaW was my least favorite part of the game, but I do like that they could throw in some really dark humor in there. The main plot was decent, with some minor issues. I didn't use different save slots to go for all endings in the OC or HoS, but I did play all endings here. In general, The Witcher 3 is one of the better games I have played lately. I especially like the attention to detail they put into the world. This game puts to shame any other open world game that I have played. It's not quite in my all time favorites list, but that's not the game's fault.
I didn't have much problem with the boss fight you guys mentioned. I did have some trouble with the third phase, but the first two were fairly easy for me.