It works
Yeah I've read that a lot here "but I will lose the s-pen when flashing custom ROM". No you will not !! Not sure why people think that, maybe they think that because it's a samsung feature it's impossible to support on a non-samsung system ? Since Samsung is using the linux kernel, they are bound by law to release all drivers. So they did, including the s-pen, so it's supported out of the box on any custom ROM !
All you need to do is download the 'markers' app from the store and after you've installed it, you have an s-pen sketch board, and after that it just works on everything else too (on the CM12 interface etc) , including air support (no need to touch the display).
The only detail that I don't like too much is the pointer itself. On stock it's a small dot, via markers it's like a mouse pointer. However I read yesterday that people are working to change the pointer, it's possible via an overlay. But then again, it's not bothering me much anyway.