There are always some common complaints;
the Gym will be too small (no matter how big it is),
there will be some mud (1000 people walking about will move soil all over the site),
the bar will be too noisy,
the weather won't be what they expected,
no matter how cheap you make it, someone will complain about the prices,
they didn't like the food,
the renegade will be too drunken,
Be aware that no matter how hard you work, you can't please all the people all the time. Those who complain are rarely those who actually contribute anyway, so love your volunteers and smile sweetly at the complainers while wishing they would just shut up.
Do your best and be proud that you ran a fantastic BJC.