As someone relatively new to Processing, I’ve experienced equal parts excitement and frustration. 0115 is a reasonably mature build, and I’m glad I didn’t try this earlier, but more advanced work is likely to get easier as the software develops, improves, and squashes bugs.

Before I dive into the full, technical explanation for those of you using Processing, here’s the Cliff Notes version:

1. Processing is great, but think of it as a sketchpad — and “beta” is accurate; prepare to hit up against some limitations that could become a time suck if your project is dependent on them.
2. OpenGL rendering works, but has major limitations when mixing pixel processing. Then again, you’ll want to use Processing’s other built-in rendering engines so you can share your work on the Web, so try those, and consider waiting on your OpenGL sketches until the bugs are fixed.
3. Video capture on Windows (and Mac, to a lesser extent) can be a pain because of QuickTime for Java. JMyron works around this on Windows with DirectX, but there is an important caveat; again, you may find things feel like a work in progress.
4. JMyron is fantastic for doing simple motion tracking without a lot of coding. (Here’s where Processing wins; Jitter and cv.jit, for instance, are much harder to use in this area.) Example image below from JMyron’s site.

Interesting example of using JMyron/Processing: Shadow Monsters [Pixelsumo entry]