Red Tree Reader was created by Red Tree Labs. It was created in about a week, and designed to as closely mimic Google Reader as possible. Damn near same UI, same keyboard shortcuts (at least the ones implemented).
Nobody likes change, because change causes unnecessary stress and discomfort. I didn't want a newer, more feature-full, next generation reader. That's why I use (used) Google Reader, and I bet it's the same for you.
Red Tree Reader provides a subset of the Google Reader functionality (the core functionality that makes it a snap to consume way too many feeds, daily). This includes things like folders, starring, keep unread and so on.
Red Tree Reader was created with a revolutionary process called FastHack2.1, which absolutely gaurantees the absence of all bugs! If you experience a bug, it is probably something you did.. you can tell us about it if you like.