We visited for the festival and I would have gave it a poor instead of an average but I don't believe it's the actual stadiums fault it's more the festival organisers at fault.
During the festival there were no bins to put rubbish, the place was filled with rubbish and no one picking any of it up. Toilets blocked up, overflowing, walking through human waste to go to the toilet. I ended up not drinking the 2nd and 3rd night just so I wouldn't go to the loo.
The entrance and exit malarkey that went on those nights was shocking I'm surprised no one was seriously hurt.