For me learning to use canvas was easy. But I had learned graphics programming when I was a kid messing with SCREEN 13 in QBasic. And a lot of the lessons I picked up then, apply to canvas today.

I found canvas is actually a lot faster than I expected. I made a little graphical Roguelike that was drawing hundreds of sprites at 30fps in all modern browsers easily even on my iPhone (some browsers on some systems are able to maintain 60fps or higher.)

There's certainly plenty of reasons to make native apps. But I was pleasantly surprised by canvas performance, personally.