Pajama: No and I have no intention of installing it. I only play single-player games and as such don't want to add needless extra bloat to my computer, all the more so when the program itself is still in a fairly buggy, beta state. I'm already annoyed that many GOG games add Galaxy dependencies when installing even if Galaxy is not installed.
Just my 2p worth :)
chevkoch: No, not interested in achievements or game time tracking. Also, I would not want to install another (apparently buggy) client when I can play my games without it. That it's marketed as optional, but offered in sneaky, hidden opt-out fashion is what made me like GOG in general a lot less.
+1 to both of these.
So long as offline, self-contained, no-net-connectivity-required DRM-free installers exist and can be downloaded via direct link in my browser (or GOG Downloader, which I'm still fond of but I guess is passe now) I'll be happy with the site.
I also really wish I could opt out of GOG "profiles" altogether, but so long as I can change all the privacy settings to "only me" I can live with it.