For those of you that missed Dota 1, you can check out the graphical difference between the games:
http://i.imgur.com/5TrNcGnh.jpg
http://i.imgur.com/44bwFbph.jpg
http://i.imgur.com/97G4gy3h.jpg
http://i.imgur.com/iD7vFUyh.jpg
http://i.imgur.com/UWnFi5ih.jpg
http://i.imgur.com/89n0CbHh.jpg
It's so weird playing Dota 2 without having played Dota 1. Dota 1 streams, which are luckily less common, look like an entirely different game.