Harry Potter and the Order of the Phoenix is an excellent game for Nintendo Wii.
First off, I must say – the entire castle and grounds are absolutely beautiful. You can spend hours just wandering around and admiring Hogwarts. The cool thing about this game is that you can actually do that. You have tasks to do, but you can pretty much get them done whenever you feel like it. I think they refer to these types of games as "sandbox" games.
I've read some horrible reviews about this game. If you're a diehard Harry Potter fan, ignore those reviews – you will love this game. The frame rate is fine, I know a lot of critics and players have had issues with that.
There are a few problems that I have with the game, but they are not really that big of a deal. First off, the motion controls are not always the best. Sometimes I'll do one spell and it'll do a different one (whichever is best for the object). For example, if you need to 'Reparo' something and do the spell for 'Reducto' instead – it will, most of the time, 'Reparo' that object. Another small problem I have is that, for whatever reason, it has a hard time picking up the 'Stupefy' spell. To do the spell, you are supposed to push both the Wii Remote and Nunchuk forward towards the screen. Sometimes it works when I do that, other times it does not. That ends up not being that big of a deal though, because there really aren't as many duels in the game as one would want/expect. When there are duels, I usually just use the other spells, (especially 'Protego' to deflect a spell back at the caster) and I'm fine. It also says in the game that if you hold 'B' while targeted on a person, they will either run away or duel you. I've actually never encountered a time when they challenged me to a duel – they always run away.
Though Harry Potter and the Order of the Phoenix has a few flaws for Nintendo Wii, it is an amazing game nonetheless. The pros that the game brings far outweigh the cons. If you are a Harry Potter fan, or just enjoy games where you can wander around and do whatever you want – this game is a must have.