It's also been available for public use for quite some time (years?)
And yes... I know it's faster. In fact I have never said anything bad about about SDL 2.0. In fact every time I badmouth SDL I make a point to say SDL 1.x because I know 2.x fixed a lot of 1.x's problems.
EDIT:
It's good to see that LazyFoo finally got on board though. Hopefully he'll take his 1.x tutorials down completely.
It is easy to port... although the windowing concept is quite a bit different to allow for contexts and multiple windows. The only API differences are those that *had* to be done.
Also, SDL 1.2 allows for hardware surfaces which is all most people care about since they use something else (OpenGL) for acceleration (although, you had to use the OS-specific window device exposed via SDL to do so. You can now open an OpenGL context through SDL which is a HUGE improvement).
1.3 WAS the same thing until they realized they couldn't be backwards compatible with 1.2 (which was originally intended). Breaking API differences had to be made so they updgraded the major version.