First of all I would like to say that I haven't finished this game. I got it 2 months ago and haven't played it for at least 1 month. No matter how much I tried to play it - it seems too... I can't even find a suitable word for this. I am a big fan of the Harry Potter series and liked the previous games very much. The first 3 were awesome, 4th was okay, 5th and 6th were also quite good. But this... this wasn't good.
The main thing that I didn't like was the change of the style. An adventure 3rd person game was turned into a shooter. If you turn on auto-aim (or something like that), all you'll have to do is repeatedly tap the mouse button. The enemies are all the same - game gets extremely repetitive. Aren't there already enough shooters? But oh well, it's the decision of the developers, and they do what they want. The game also offers no freedom that we used to enjoy in the previous games (even in the 4th game there was more freedom!). Exploring the castle, running around different areas, SOLVING PUZZLES! The invisibility cloak mini-quests were supposed to make the game harder, but they just deepened my bad feelings towards this game.
Since the game was turned into a shooter, I could've expected there to be good graphics. But no, the graphics were barely improved from the last game! The annoying side-mission which were absolutely in no way connected to the book were responsible for the fact that I didn't complete the game. Oh and another thing - what's the point of different spells? All of them were the same. There was no need for me to use protego sinceit just delayed Harry on getting hit.
Now about the positives (there really weren't many). Even though the game didn't follow the storyline very closely, it was still structured according to the book. At least by the major points (such as the ministry of magic, the Godric's Hollow etc.). The graphics weren't THAT bad (but should've been better). And of course another positive point is Harry Potter.
My review may be quite biased, but I wrote it based on my own opinion. Feel free to disagree with me! I raised the score I'd normally give a game like that by 1 point for being a Harry Potter game. As I said I am a big fan of the books, movies and PREVIOUS games, but just by being a fan I couldn't give this game a good score. It just doesn't suit me.