The chairs are plastic but the arrangement is usually two rows flat on the floor, then two rows behind on one raised plinth, another two rows behind on a slightly higher raised plinth etc. If you are in any second row behind the first on any plinth, you won't see much. Frankly, the raise isn't high anyway each time, but the second row really suffers, I find.
Damn, should have read the board before booking! I ended up with row D for £20 via TodayTix, which means I'm not going to see a damn thing.