For me, it's not worth buying until it's $20 or less. Mostly because it gives you 20-30 hours of gameplay and the replay value isn't necessarily high once you beat everything..because everything turns out the same way in the end (or so I've read). So just one big playthrough and then it's over...that's not worth $60 for me anymore.
After you complete a case, there are case notes at the bottom that basically tell you, "if you said this," or "if you got to this place earlier" or "if you presented this piece of evidence" it would've yielded different results. I'm not paying attention too much during this play through so i'm definitely going to play through it again more fluidly.
My biggest problem right now is finding time to play through it. Its like sitting down and watching a TV show. I feel like I need to sit through a whole case before I can put it down and work.