Have to say, I am surprised that people have negative things to say about this series. Personally, I have been waiting for something like this to come out since 2005's documentary "Alien Planet." If you want to find serious documentaries about what alien life might be like, there is a complete shortage for you. Every documentary about aliens lacks anything substantial about how alien life might evolve on different planets. Alien Worlds (and Alien Planet) provides this in a wonderful way: CGI. While I am not usually the biggest CGI fan, it is the perfect medium for bringing to life scientists' predictions of biological evolution on exoplanets. For instance, one planet might have an atmosphere so thick that beings can float around endlessly. While I could use more time on the alien world in this series, there is still a very substantial amount, especially given since no one else has really made anything near this in 15 years, and had never done so before that.