I have it on PS2! The first thing you will all notice is the graphics. They are amazing and totally blew me away. Especially the opening titles they look so real!
The first thing you need to do is join a Hogswarts team. There are the four houses and Harry, Draco, Cedric or Cho will guide you through the basics of the game. You then pick each member of the team (yes they have Angelina and George and it's all very well worked on) and depending on what the part in the team is you get taught on how to work each section.
In this part (say your training to be seeker) you have to chase this sort of snitch bug as Harry/Draco/Cho/Cedric guide you and tell you what to do. This is the same for Chaser and Beater and so forth.
Then you get to play a Hogswarts game (in snow, rain or shine). You play as a chaser, then you can switch to a beater and then near the end of the match you become the seeker and have to catch the snitch.
Once you complete this you move on the international. You play in ice arena's and so forth and yeah...it's really good!