I went to the opening night of U2. The place is amazing. Any issues with the sound are due to operator error. It was stunningly clear from every seat.
The only seats to avoid are the 100s beneath the overhang and the very last row of the 200s. These are the only seats you cannot see the entire screen (ceiling). If you have a choice avoid the very end sections, there is really nothing wrong with them but you do get a bit of that edge of screen effect. Second section in, no problems at all.
As for motion sickness, YMMV but it really depends on the graphics being shown and how you choose to perceive it. There was a brief moment in U2's show where the place felt like it was rotating. If you focus on the seating for a brief second, it will stop.
Definitely go before it becomes second hand and run down even just to see the Experience movie.