I finished LA Noire last night... I bought it two weeks ago this past Monday.
Honestly probably the most gripping storyline of any game I've ever played. The gameplay was just so-so but like a good book I couldn't put it down.
It took me right at 22 hours to finish the main storyline plus DLC, with right at 70% overall sync. I didn't do most of the side missions.
IGN gave it an 8.5. I'd say that's probably about right. That puts it in the above average range, but not quite on par with other Rockstar titles. It's a solid first installment of a franchise (assuming they're planning sequels), and there's plenty of room for improvement. Sometimes it takes studios a sequel or two to get it right (see Assassin's Creed- based on the first game, I never would've imagined myself spending a dime on a sequel, but now I'm sure glad I did).
On a related note, I've just now started watching
Mad Men on Netflix. It's weird seeing the guy who played Cole Phelps on a real show.