Here is a new opinion, listen to what Johanna had to say:
"Hi!! My name is Johanna Johnston, and I am 13 years old, and I live in Chatham, Ontario, Canada. For my birthday, I was given the 'Speca Cage' and a few add-ons, one of which was the space observatory. I used the space cage to replace my hamster, Cinnamon's SAM cage. At first I thought that it was wonderful, Cinnamon went straight to making his new bed in the 'Observatory'. But then I noticed that it wasn't working for him; the wood chips continuously fell down the hole in the center. But still I figured that he was happy enough, so I left it how it was. Then, the next morning I noticed that the top of the dome was all foggy. I pretty much ignored it until later that day, when I took him out to pet him, his fur was all wet and smelly, and he was noticeably warmer that usual, because there wasn't enough ventilation. I think that the reason for this is that because there are hardly any holes in the dome, and no holes in the tubes."
Hamster satisfaction: 
Maintainability:
Owner satisfaction:
Here is what I have to say:
The ultra-cool Sky Tower / Space Observatory is a good buy since it provides easier access to pamper my hamsters. I prefer the cover which can be opened easily as compared with the Solarium (it's like removing a cover from an "easy-to-open" jam bottle). This accessory can be spun around with my hand and it's bowl-like cover can be used to carry a hamster (don't let your hamster fall off though). The hamsters do enjoy the attention.
The only minus point about this product is that there is little space for sleeping - though not a real problem to my hamsters. In addition, two of my (male) hamsters actually managed to push the lid open... talk about "easy-to-open" jam bottles. Make sure you close the bowl real tight!
Hamster satisfaction:
Maintainability: 
Owner satisfaction:
