I'm a big fan of Steam. In theory I prefer Impulse, since they don't add DRM, but Steam has a lot more games, features, and bigger sales, so they tend to win.
Digital download is a big plus for me. I hate having to keep tracks of discs, CD Keys, and Registration keys, and Steam largely does away with that. Sure, I can't resell my games, but that's not something I do anyway.
The only complaint I've ever had about Steam is that they can be slow to patch lesser-played games. It took a long time for Eschalon Book 2 to get their 1.04 patch on there. When I was playing Sacred 2, it took Steam 2+ months for some of the patches, and during that time it was impossible to play on the official servers since you needed to be patched to the latest version to do so. It's rare that something like that happens, but it does happen, and it's frustrating when it does. Whereas on Impulse, they don't add their own DRM, so if the publisher releases a patch, you can just patch it yourself.
I'd definitely recommend Jeff not ignore Impulse as a distribution platform, though.