Looks like a good little home.
That's definitely fine for mice or dwarf hamsters. I have a Crittertrail 3 and a Crittertrail Mini connected together with two mice living there. There's tons of room. You could house probably 3 or 4 mice in what you have, no problem. Just be sure and get females, male mice are a HUGE PAIN!!!
And if you get dwarf hamsters, don't get winter whites. They have furry feet and have a hard time getting up the vertical tubes. Campbells are very similar to winter whites only they come in more colors and don't have the furry feet. Not that winter whites are bad at all, I have one winter white and one Campbells and they're both very, very sweet. My mice love their tubes and having different rooms to hang out in. 
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Kadee Sedtal
"I wish I had a dollar for every time I spent a dollar, because then, yahoo! I'd have all my money back." -Jack Handey