It's a good game, but it's very short, and offers little replay value. You could probably have the game completed in a couple of days, easy. I got it after a price drop for about a tenner, and would not pay more.
If you are a fan of the show, check out the game. Has moments that really make you feel part of the Lost world. Some of the actors from the show provide the voices, some don't, strangely.
As for the people saying they had performance issues, I have a mid range system, and had no problems playing this on high graphics settings. Just check the minimum specs before buying.