it's $24 now on Steam
I think it's worth it. Arma 2 is actually a cool game. I pirated it, liked it, and then copped to play it and Day Z
just know what you're getting into. it's an unfinished mod that's being constantly updated and changed. no one knows where it's going, but it's most likely going the stand-alone direction, and probably won't be a mod for Arma 3. as it is, it is buggy, and you might spend dayz collecting cool shyt, only to lose it all because of a stupid bug. but it's an 'alpha', so really you're not "playing", you're "testing". if you're easily frustrated playing a semi-broken game, it's probably not for you
all that being said, I like it a lot. it's an experience I've never had in another game. IMO the real appeal isn't the zombies, it's the other players. when I see another player, I have so much to consider: did he see me? is he friendly (yeah right)? is he alone? does he have something I want? can I make this shot? what if I miss? will someone else hear the shot? will zombies hear it? maybe he has a camp of vehicle near by, should I follow him? through all this my heart is beating like crazy, cause I know my decision could mean then end for me. and I've been playing solo, so I imagine it gets more interesting with more peeps
tl;dr - I like it