I just watched the video tutorials and I'm pretty impressed by not only what you can do, but how the controls seem to be evolving from the original Nik tools. I'm hoping things like the on-screen guides for vignette and other zone-specific effects find their way into Color Efex and Silver Efex. I also love that you can combine the pieces from the various camera types easily even when one type doesn't contain that filter effect by default.
I was prepared for a so-so batch of Instagram-like filters with a little extra, but these are very intelligently put together, and extremely powerful. Kudos to Google for not only making this available, but shooting it out for free to current owners (or at least some current owners - I need to boot up the Mac and see what's what!!).