Midnight launches are stupid. Unless you have a nocturnal sleep cycle and will be up all night, then what the hell is the point? You'll get home, install it, then play for like 45 minutes, just enough to get interested in it alot, then either you have to go to sleep and pick it up again tomorrow, or you stay up later than you should and be tired and miserable the next day, then when you play tomorrow you'll be tired and grumpy.
It's just dumb.
Unless you're a hardcore gamer, and absolutely need it on it's first night, I wouldn't do it. I just don't see the point of gamers hanging around the entrance of Gamestop, or even WalMart, for hours until they start selling the game.
That's my honest opinon, though.
Midnight launches rarely happen in my city as no one goes to them. Once upon a time when Canada received short shrift on the shipping from the US suppliers, sometimes you'd want to get to the store as early as they were willing to sell it just to make sure you could get a copy, from anywhere, on launch day. If you missed the first shipment, back then maybe you wouldn't be able to find a copy until the Thursday or Friday of that week.
But all that's fixed now. Walk in to any brick and mortar any time on the Tuesday and there will be copies (usually).
When I was in University I went to the midnight launch of Halo 3 with my friends because we were bored and it was a Tuesday. We bought the game and immediately went to sleep, really no point of getting it a midnight. If you intend to play the game go for it.