I am not a photographer so pardon my ignorance. But I wd imagine if the sizes were a bit varied and the falling action also showed more angles, the 'all' in the title wd be more truly represented in the visual. Just my humble, amateur opinion.
I like the abstractness of this photo. I agree that you should have found a way to make the reflection line across the bottom more horizontal, but it would be cool also if you took it the opposite direction and used a sharper angle to the dominoes so that they went from large to small moving left to right. I know it can be tough when your shot has an "evil twin" in the challenge. That seems to help one and hurt the other, but you were lucky to be on the receiving end.
I think that the comment about them looking like they are standing up has to do with the lighting and long exposure. A second synch flash might have helped the "after" image be stronger than the "before". I had to find a way to fake that for my motion shot.
Nitpick: It would be nice if you could have achieved more even lighting as there seems to be sort of a spot-light effect going on. The lighting is strongest in the center.
Overall, it is obviously a strong image that many people liked. I like the black and white, but actually prefer more organic lines. The strong verticals are just a little too stark for my personal taste, but I can appreciate the photo and the work that went into it.
Seems like the camera was not perfectly parallel to the dominoes. Notice how the length from the edge of the photo to the dominoes becomes larger as it moves to the right. Just something to keep in mind for next time; I have a problem with it in all my photos. Good use of grayscale.
Excelent shot. Definately showing motion and I love the use of black and white here. Your angle and framing/cropping are great, and lighting is very nicely done as well. Great shot. One of my favorites in this challenge. Good luck in the challenge.