Having bought and played all of the other 4 games, plus the Quidditch World Cup - which I enjoyed more than I thought I would; I loved the way it went back to being able to explore Hogwarts like the first 3 games.
I did like GoF, but found the inability to explore Hogwarts frustrating. I did play it endlessly though, so it wasn't too bad.
The only negative thing about this, is that I can only play using the keyboard and mouse, as it refuses to recognise my Microsoft joypad, which is unusual, as all the others recognise it. It means Harry is very hard to control, as to make him go in a certain direction, you have to aim the mouse to make him walk that way, which for a while, because my mouse is optical and very sensitive, it meant him walking round in circles!!!!!! I am use to it now, but would prefer the use of a joypad.
The spells are good, and I like that I can now do hexes against unsuspecting students! I managed to get detention from Snape for hexing a Slytherin!!!
The graphics are brilliant, and there is so much to find throughout the game.
I just wish my joypad worked!! Although, I must admit, it would be difficult to produce all the spells with a joypad.
Aside from the joypad issues, I have enjoyed this game so far, and can't wait to get to the Ministry bit!