The cons out weigh the pros with this one. I'd rather room with somebody I know and pay an extra $100 than have my weekend ruined by doing share accommodation with some stranger I don't know that I don't get along with just for the sake of saving some $$$.
This is coming from somebody that used to set up similar things on these forums.
The first year I organized acomm via these forums (Brisbane 09) the place we ended up at sucked, a few people ended up dropping out which meant some other random backpackers were thrown into our room (and used our towels
), we had a girl that wanted to bring cutting knifes and was making a big deal out of it.
The second year I organized acomm I placed a rule that you must have at least 500(?) posts on these forums. Kind of a test of dedication. And everything worked out well.
So yeah, while rooming with randoms might seem fun and cheap, A LOT of planning needs to be organized before hand.