I've done it. It's pretty fun, actually.
There are people who super get into it and make it kind of weird. There's a lot of normal people too. It's basically like playing a table top RPG but being much more theatrical. There's the aspect of the game where you're, you know, playing a game. You have stats and you gain new abilities etc. Then there's the aspect where you play a character and see where they go.
Some groups are really into just fighting and some are really just into the actual roleplaying aspect of it. If you can find a group of somewhat well adjusted normal people, I'd give it a try if you've ever thought of it before. It's like any community though, there can be some really awesome people willing to help you out and explain how things work and there can be some really terrible/annoying/creepy people.
Point in case: the people I played with paid for my first game to convince me to try it, fully knowing that it's not for everyone and you can't really figure out if you like it unless you play it (if you're sitting on the fence that is).
The best groups will take it seriously as in they'll really try to get into character in order to have the best time they can. They also know that it's just a game after all, so they don't let it boil over into real life. Anyone who does is considered just as crazy as someone who's never LARPed would think they are.
I've written way more than I expected to, which makes me come off as coming from the lowest level of nerd hell, but oh well.
Looked hilarious!