To board, you enter in to King's Cross Station where the lines must get rather long, but we were able to walk right through.
As you get to the end of the line, there is a corner where you get to see others disappear as they go through the wall at platform 9 3/4. This is super easy to miss (and, in fact, we did and had to go back!) but is fun to do.
Afterwards, you are squeezed through a tunnel and come out to see the Hogwarts Express in all of her glory!
Even though the train does take you back and forth between the parks, it's more of an experience than a ride! The inside of the train cars look exactly like you might imagine and there are things happening on both the doors and the window. Also, each way is a different experience so it's important to go both ways!
Up next- Hogsmeade! And then our month of Harry Potter will be over : )