I attended the final dress this afternoon.
In terms of the seating, yes, the black boxes are pillars. However, since the show is in a round, it's all center; the pillars don't really block anything. I saw up, sitting on F4, which was a fine view. I'll be on the opposite side in seat C21, when I see it again in a few weeks.
The cast walks around the stage for a lot of the show with only a couple of block set pieces, acting as a desk, chairs, a bar table, and bar stools. If you're sitting in the ABC 10_ and ABC 20_ sections, you get a better profile views than in the ABCDEF Odds & ABCDEF Evens sections, which either full facing or back facing views were more common.