You're not forced to pay membership, but the option is still there for the peoppe with money. I'm sure you can get a bunch of exclusive shit and whatnot.
There's been some speculation about the game giving viruses and stuff but I don't know whether this has been addressed or not.
I know these answers aren't really that complex, but I'm just not a big fan of the game. It looked interesting, but as soon as I saw that you have to be online to play, I avoided it like the fucking plague.