Lego Harry Potter Years 5-7 is another LEGO game. There isn't much that will surprise you and unlike, say, Lego Star Wars III, your fondness for the source material will go a long way to determine how much you enjoy it.
I'm not writing those first two sentences as an insult. I think the Lego games are a really good times. They are simple affairs that are hard to fail (OK, if you don't use invincibility, they might be much tougher to deal with in spots) and manage to make replaying levels not all that tedious, even though you have to do each level at least twice to get everything. They've improved the hub world even further from its terrible debut (Lego Indiana Jones 2 had issues) and there is a wealth of things to do and find there as well.
Again, as with most Lego games, your fondness for the story material will determine, in large part, your fondness. A Lego Twilight game would likely make me wish to slit my own wrists, but Lego Harry Potter is quite enjoyable. Splitting the characters into a few groups gives you reason to use some of the more obscure characters. It is visually, well, Lego. It won't be mistaken for a visual powerhouse and I'm curious as to what they can do on the next gen as I'm not these visuals will be acceptable on a new console generation.
I think the game is well worth attention, minor gripes aside. If you've played Lego before, you will know what you're getting into. The story telling is a bit tighter than usual and the usual enjoyable really light effort gameplay is back. They have less Hogwarts than the original, obviously, and it was a concern since it is such a great locale --- but their environments they used is top-notch.