Not only does the campaign provide a forgivingly gentle introduction to the initially daunting complexity of Prison Architect, it also tells a surprisingly gritty and compelling main story. (heypoorplayer.com)
Gameplay: A nice gentle introduction to the genre with relatively easy puzzles and mini-games. (gameramble.com)
I started in the 50cc class, and it is a very gentle introduction to the game. (thereticule.com)