Well, that's up to you. From what I know at this point it's about 20 - 25 hours in length. It brags that you never have the same game experience twice, which is supposed to make you want to play it again and again (although I'd imagine one more play through is all you'd need). There are a few choices to be made that will change the outcome (or, at least, one major one). So, again, I'd say most people will want to play through it twice.
Most often I base game purchases vs. game rentals based on the time needed to complete it. That's why I've given you that info first. If you're wondering if the game is good
enough to buy, I'd say definitely. Car1 and I have already cracked up about the amount of time we've spent reminiscing over the 20 minute demo. It's just that good.
Then, of course, are the handful of "perfect" reviews the game has received:
So, yeah...I'd call it a "buy".