There's audio commentary in the collector's edition, and I really loved the audio commentary in Orange Box so I'm thinkin about it.
Is it all the way through the game, or is it just at certain parts? Is it good?

It gets triggered at certain points and so far, they seem quite frequent. It's good in terms of technical details and how they came to make certain art choices etc but it seems lacking in narrative discussions, I say that only on the end of Chapter 2 so it easily could pick up in that respect. I imagine that would have been better if Sam Lake was involved but either way, it's very interesting and I highly recommend it.

Ok good, that sounds like what I thought it'd be.