Little Snitch was effective, but overly complex for the average user. I'm sure it's great for someone who configures networks on a regular basis, but as a Mac user, I just want to use my Mac. If I wanted to twiddle with security settings all day long, I'd still be on Windows.
This looks like it might be a good, simple, replacement. Hopefully as it evolves it doesn't get swamped by feature bloat.