They have nice getting started guides. Try it and see. It's... really pretty simple. There is a reason they've built a trillion $$ company - they've done a great job.
I'm sure CUDA is great, and if I had more free time and/or better reasons to improve the performance of my code it would probably be great for me. My point was mainly that a few lines of code which may be trivial for one person to write may not be for someone else with different experience. Depending on what the code is being used for even a vast increase in performance may not be worth the extra time it takes to implement it.
[0] https://docs.nvidia.com/cuda/cuda-c-programming-guide/index....