it seems like it's set in the same era as the Mafia games (America 60 years ago), so i'll just play Mafia II ! 
And i have GTA 4 and RDR to enjoy Rockstar's open world masterpieces.  
And it says on the game's page that R* are only publishing it, and not developing it in one of their studios ..  "Team Bondi" are developing it =/
 
So, what am i missing about this game that makes it any different or interesting ? 

Um...You play as the cops?

Hmmm, never heard of it. I just looked it up in our wiki now, and it looks pretty good.

Maybe you should do your own research instead of making pointless forum topics asking people to make you want a game. Do what you want no one cares if you buy L.A. Noire or not.

Transfer 60$ to my paypal account and I'll send it right away!

Seems like it could be a great, gritty detective game as long as it doesn't get all gamey and have you shooting all the time.

It sounds like they're really trying to make something different with LA Noire.  How it turns out is very much yet to be seen, but it could be amazing.  I'm hoping for Heavy Rain + Tex Murphy myself.  Probably more will be known at E3.
 
As far as selling you on it, I'm not sold myself.  I have to know more about the game, but I can say this.  From what I've heard from a bunch of sources, Mafia 2 doesn't seem to be turning out real well.  That might turn around too, but it doesn't sound hopeful so far.

" Maybe you should do your own research instead of making pointless forum topics asking people to make you want a game. Do what you want no one cares if you buy L.A. Noire or not. "

I can't sell it to you yet.  Street date is in October.   =  /

The LA Confidential vibe is interesting and, again, you're playing as cops. It's too early to sell anything about it. Hopefully they'll show it next week. 

I am not sold on it myself yet. But it looks interesting and I am far more likely to buy this then Mafia II at this point which is a game I currently have little interesting in buying.

Don't buy it.

To be honest, even if it bombs critically, I'll probably pick it up just to check out the facial animation.
http://www.edge-online.com/magazine/open-world-confidential-la-noire