I'm trying the lower deck this year (fewer steps for bad knees), but a lot will depend on the angle. On the upper deck I could still see a lot of the field between peoples' heads (I'm very short) but the angle of sight from that 3D looks very flat. I may find myself watching the games on the big screens despite being in the stands.
Gonna keep trying until I find the perfect west side seats. I wish I could have mirrored the east side seats we had 2 years ago; 4 rows up on the 40 yard line. But after 15+ years of moving around the east side, just couldn't take the sun in my eyes any more.