Yup!  Enough said people...

So this is the result of all that work on the two consoles?

Nice one AMD. I hope this is similar to the API on the consoles so devs working on multiplats won't have too much difficulty using this on PC.

Strange how the new console development has helped PC gaming.

It helped PC gaming alright but I think this helped out AMD more if you know what I mean. ;)

It works alright but how about the performance impacts ? Nvidia also has to worry about devs choosing light indexed deferred renderers instead of tiled deferred or regular deferred renderers. Just because all these effects can be ran on nvidia cards don't mean that it will run good. :)

Any card that is basically not a GCN card will encounter some performance issues with tressfx (This includes AMD's older HD6000 series and under too) but seeing as how you have a gtx 690 that was mostly no problem for you. Depends on how you define "trouble" and I mean trouble in the sense that AMD can now play extra dirty against nvidia potentially. Got to remember all of these consoles are now under AMD's mercy so if anything I can see AMD calling alot of shots LOL. I dearly worry for nvidia users too seeing as how this is a big threat to their experience on geforce. I seriously hope AMD was about open source and integrity otherwise they were all just talk because what AMD could start doing is having games exclusively use the mantle api only therefore possibly locking out nvidia owners too which sucks. 

This really just sounds like a direct API to the AMD chip which would be no different if Sony did the same thing for their chips. Basically what this means is that developers have 4 APIs to choose from. This API, Direct X, OpenGl and whatever Nvidia bring to the table.

Will nvidia even bring their own api ?

Or, nVidia might just support Mantle, it's Open source remember.
Direct X and OpenGL are high-level API's, they are designed so that any developer, regardless of financial position and experience can easily tap into it's feature set, of course it does come with a performance penalty.

Mantle is a low-level API, where it's closer to the metal and requires longer development times to make it work, but comes with a minimal performance impact.

This is also the same choice console developers get too, they can "tap into" a high level API, like Direct X on the Xbox or OpenGL on the Playstation or they can use a low-level API similar to that of Mantle to extract maximum performance.

AMD isn't out to replace Direct X or OpenGL, they are just giving developers a choice, remember developers requested this from AMD, AMD didn't do it to ruffle everyone's feathers.
If nVidia does support Mantle, then that's only going to mean great things, if you go by history though, nVidia hasn't really supported many of AMD's "Open-Source" technologies untill it was included into Direct X. (Like AMD's 3dc texture compression.)

I believe Nvidia already have their own APIs.  This is really sounding like we are going back to the 3dfx days where each card have their own APIs and extensions to openGL where developers had to decide which one to use and support.  DX was brought into scope to fix that problem.  Since Nvidia and AMD cards still will be sold in bunches, developers concentrating on GPU specific features that are not supported on both cards is the same as 3rd party developers doing the same thing with Sony and MS console.  

I will have to see all the info on this API.  Just being lower level is no different than adding extensions to OpenGL for card specific features.  It sounds more like a pain in the but for developers now having another API that is not stardard across all cards.  Since developers have to support either OpenGl or DX, having some mid tier that will probably only work on GNC cards is another thing they have to decide to use or not use.  If the balance of PC cards still have a lot of Nvidia cards out their, where would be the incentive to use a low level API when you could do the same and use Nvidia low level API.  

DX and OpenGl was made to not have to use such APIs that are specific to one card vendor.