"I've had my hamster, Rico for about a month and a week. Let me tell you he LOVES the cage, especially the wheel! He loves climbing up the tube that goes into the petting zone, and he never seems to get bored in this thing.
The only disadvantage is that he brings his pine bedding and food up into the Xtreme wheel. Then, when he runs, it goes all over the place. However, Crittertrail was smart by adding that little "tray" underneath underneath the wheel. Even if that doesn't work (it didn't for me), all you have to do is take the top off one of those giant copy paper boxes and put it underneath the cage.
I highly recommend that you buy this cage for any Hamster, Dwarf Hamster, or Mouse. I guess it would be O.K. to buy it for a gerbil, but they have a tendency to gnaw on things a little more. Make sure that if you put your gerbil in this cage, that they have a lot of chew toys, as chew toys are imperative for all rodent pets, but especially gerbils.
My opinion? Overall totally awesome cage :)"