I have had a couple, and they are nice but a pain at the same time. If you stack them, I found that condensation built up on the lower vivs, way too much humidity. I didn't like bedding getting stuck in the tracks, and its hard to use all the space well as the tray curves upward making it hard to put things in the far corners. Do not keep hatchlings in this as they can get out between the gap in the doors (unless you use the center divider as it is a tighter fit). They look nice visually, but if you stack them, make sure the surface they are on is stable as they look as if they might tip easily.
I didn't end up keeping mine long. As a matter of fact, I have one left I still need to sell. I should get rid of it so I have more closet space.
Good luck in what you decide!