Having both coached and refereed youth soccer, I was impressed with the simplicity of the rules, only 18 (thinnest rulebook in existence, I'm sure). Other than "measurements" and positioning -- out of bounds, goals, etc. -- all the rules regard the safety of the players. In addition, the origins in England are obvious because even though the game is played in countries most of which use the metric system, all measurements of the field and goals are English.
Wonderful game, a must buy for our family.