It was an "adventure" when you were a kid, one of the longest trips you might have been on.
Sitting on blankets on terraces, often under plastic sheeting as the rain fell, with the echoey voice from a tinny speaker droning on ... nothing better for a good sleep honestly.
Plus that special "I can't believe it's not chocolate" mint hellas bars to buy!
The teen+ years are then about talent spotting (I can't complain, I picked up a wife a Maine Road assembly)
Past that though and they are boring as hell. I can't imagine why adults, especially elderly ones, go to them.
I distinctly remember the last assembly we went to in Manchester. It was hot as hell and my wife was heavily pregnant at the time. We went for a walk around the concourse to get some air, and found an empty chair she could have a rest on. Immediately, some spotty faced brown-shirt-wannabe attendant trotted up to tell us that the chair was for attendants ONLY. He seemed quite shocked when I told him, very loudly, to Fuck Off!! (pretty sure that echoed round the walk-way, LOL)
We went home, we never went to another as far as I can remember.