DirectX 12 seems to be a very common topic of discussion at the Game Developers Conference this year. Remedy was one of the developers that held panel discussing the upcoming API, using their experience with it while working on the upcoming Quantum Break to share some tips, suggestions, as well as general takeaways.
The most important thing that Remedy said, and appears to be a common theme with DirectX 12, is that it is a far lower level API than DirectX 11 was. This means that it is ‘closer to the metal,’ in turn leading to developers needing to program and substitute for drivers themselves on a case by case basis. And while DirectX 12 can lead to massive gains in CPU and GPU performance, developers need to separate the two in their calculations.
Because of all of these changes, DirectX 12 can be hard to get a handle on- doing everything right can lead to developers matching DirectX 11 on the GPU front (though other developers have promised gains as large as 10%), and outperforming DirectX 11 on the CPU front; however, doing everything right is not a given, especially given the compatibility issues that existing GPUs may have with how DirectX 12 works. It is very easy to mess everything up, and that can be costly. Therefore, a developer needs to be able to commit to DirectX 12 entirely, rather than trying to half ass it.
It sounds that DirectX 12, while certainly netting developers a lot of benefits, will definitely have a steep learning curve to it as well.