Buying? Maaaaaybe.
Its a story game. Its decently long, and it has a fair replay value.
But to me, its not worth buying, because its a story game. Rent it twice, maybe even 3 times. Run through it all you like. But at the end of the day, a story game will almost always be a story game. Theres only so many ways it can end, and only so many ways to get there.
I personally would have bought it if other games werent higher on my list. (The Skyrim collectors edition is soaking up a large sum of my cash, saints row 3 is a must buy, and im going to get either BF3, or MW3. As much is i DONT wanna buy either, i need a new shooter. And that are really the only two viable option.))