I have also only been to two. The first was for GTAIV and some chavs started giving hassle because they thought I was pushing in the line when I arrived. An elderly woman approached me at one point with a small child in tow and asked "Is this the line for the Grand Theft Auto?" And they blame us when young children get their hands on 18-rated games.
The second was for Resident Evil 5 and it was entirely uneventful but the taxi driver on the way home was talking on his phone while watching a DVD on a portable DVD player on the passanger seat. He seemed to value basic safety while driving, keeping his eyes on the road for as little time as humanly possible. I fell asleep not long after getting home so it wasn't really worth going for the midnight launch.
I kinda went off midnight launches after that. There was no real excitement, just standing around very tired and paying £16 for the privilege of going home only to then fall asleep and not play the game until the morning anyway.