Well, it's over. The last Harry Potter movie. Granted, it was over in 2007 when the final book was published, but there's something different about the Potter movies.
More than Lord of the Rings (8 movies is more than 3), more than Star Wars (because there was so much of a gap—in time as well as style and story—between the two trilogies), the Harry Potter series created a world with rules. Especially as the visual technology improved (just compare the quality of special effects in HP1 to those in HP7pt2), it was a world in which we came to expect certain things.
Stairways shifted, paintings were alive (and that's an idea I particularly love), space was malleable to an almost-cartoony sense (see the Room of Requirement), other people's memories could be experienced first-hand, and even typography was mobile.
It was a world rich in history (as clearly emphasized by the thick layering of paint on Ollivanders) and full of life. I will miss exploring the halls of Hogwarts, wondering where the next secret panel or hidden doorway will be.
If nothing else, it was immersive. I'll miss it.
p.s. I did like the books better, but there's something to be said for seeing the worlds you've read about.