I have used visionariums in the past. I bought two so I could stack them. I ended up selling one because the one on the bottom had an insanely high humidity. So I will not be buying more in the future. Its a bummer to because I bought them for the stackable feature. And I live in Colorado, not known for its humidity. So in the future I will buy more 30L instead, which are much cheaper than these cages.
Pros:
Can put 2 snakes in one viv - there is a cage seperator you can snap in
I like the sliding glass doors, look good aesthetically
The plastic pan makes them easy to clean
Cons:
Humidity is very high in the lower vivs I have found.
Aspen gets stuck in the cracks where the doors slide
Seems to have poor ventilation, especially the cages on the bottom
With the cage divider in, it makes the inner door hard to slide
I would think that these cages are good for adults, as they are the same size as a 20L. But remember, thats just a MINIMUM enclosure size for an adult. I think that they would be good for smaller adult corns and yearlings. Honestly, I should have put my money into a regular 30L for the same, if not cheaper, price. What makes them nice, is the stackable feature, which is why I bought them. But because of the high humidity in the lower cage, I was worried about the aspen molding.