It is very similar in design to Spider-Man or Transformers as far as you switch between real 4d sets and effects and projection screens. However, you are sitting in Soar'n type seating only you can't see the people around you or your own feet which hang down. It's fairly dark inside, and you basically fly through different parts of Hogwarts both indoors and outdoors. For instance, you go through both the the quidditch pitch and the chamber of secrets. The ride movement is also much more intense than Soar'n you move much farther up and down and side to side. You also actually physically move around the ride enclosure, whereas with Soarin you basically stay in the same place and movement forward is only simulated. It's a very immersive experience when you are going through the real scenery with props all around you, above, below, beside, and behind you.
I very much enjoyed the ride, but it also made me very sick, and I'd never do it again without Dramamine. The first time it wasn't too bad, but the second and third times it made me feel very sick for hours. I think what I loved so much was not that it was HP, even though I'm a huge fan, but that I'd never experienced any attraction similar to this before. I loved the immersive feel like I was actually taking part in the movie and not just watching it.
As far as the queue line, it really is as much a part of the ride as the ride itself. Doubly so if you are a HP fan. The line winds through the castle and along the way you get to enter different rooms and meet different characters. For instance, you get to see Dumbledore in his office. You also get to see all the portraits on the walls as you go up the stairs. The characters are holograms that give little speeches that set up the plot of the ride. It's fun to explore the details found in these areas and to know the plot if you are a HP fan, but not necessary to enjoying or understanding the ride if you aren't.
What we did, and I would recommend to others, was take the tour only version of the castle first. This let us really explore the castle at our own pace. It was interesting because if you stop and listen to multiple playings of the characters little speeches, you will notice they say different things and different things happen around them each set. It was a lot of fun to explore slowly at our pace. Then we went back and used the singles line which does skip most of the castle, but that was fine because we'd already experienced it at our own pace.