It's a lot of fun, but flawed… just like every other good game. The animations are amazing. Even walking up or down stairs is convincing, not a treadmill-glide. The faces are fantastic. Voice acting is as good as it gets. Lots of actors and not once have I heard a bad one, or terrible line-read. The dialog is great, and the crimes and language are very, very adult. Grisly and brutal.
The interrogation parts are a little sketchy. They have a neat idea but haven't nailed the execution of it. When you get it right and catch someone in a lie and have evidence to back it up, it's awesome. But sometimes you end up with reactions that don't quite make sense, and it's puzzling or frustrating.
The action sequences range from good to bad, mostly OK. I'm around halfway through, and haven't repeatedly "failed" an action sequence yet… I gave up on GTA IV because of the difficulty and frustrating controls. And in LA Noire, you can skip an action sequence if you want, so you'll never be stuck on a mission because you're bad at driving or shooting for instance (F*cK you, GTA IV…)
A good part is the pacing. It's generally very slow and methodical, but then suddlenly something happens and you're off on a foot chase or car chase or a shoot-out. I love the way it goes from slow, everyday life feeling to heart-pounding police action. Seems realistic. Pretty good stories so far. I like that some of them are even pretty simple. Not every case is a complex mind-bender… again, it feels realistic this way. The cases are just now starting to become part of a bigger story, so it's not simply a string of random police work. There's flashback sequences to WW2 that are well done, but seem kind of pointless. Can't say I look forward to them but they give background to the main character and I hope they become more meaningful eventually.
Overall, very enjoyable and extremely well done. No crashes or glitches so far. But I keep thinking "They'll do THIS part better in LA Noire 2"… which is something I sadly think of whenever I play any game.
Edit- A few other thoughts: For some reason you run fairly slowly, but can effortlessly climb up a pipe on the side of a building. Why include pipe-climbing? Just silly. The action sequences seem smartest and best when they're quick. There's a big shoot out in an enormous abandoned movie set that just goes on and on. Becomes a bit silly. I was able to complete it without getting killed the first try, so it's not that it's difficult, just that it stretches believability.
The buildings and the city of LA in the late 40s is spectacular. Many diverse locations, from elegant night clubs to a hobo camp. Lots of dive bars. And the best looking laundromat in the history of gaming!