Pretty much everything has been said except:
Lots of the cages sold for them are chinchilla cages, and so have wire floors, dont get these cages or your degus will get deformed feet, its called 'bumble-foot'. Some people find a cat litter tray that is a similar size to the bottom of the cage so the degus have a solid floor
As said above they are prone to diabetes, I wanted to mention that they are so prone to it they are actually used for diabetes research.
Get two that have lived together for a long time, or siblings. They can squabble a lot.
Provide branches and they will leap around them like little squirrels.
But make sure there are no huge drops, as in put platforms at the open spaces so they cant fall too far, one of mine died from falling awkwardly.
They are noisy, would not reccommend for a bedroom. They are not supposed to be nocturnal but mine decided to wake me up most nights!
Get a very large wheel. They like to run in it side by side
So cute!
If you are in the UK, look on Preloved, its a site of classifieds ads, and last time i checked there were quite a few people selling or giving away degus with their cages! Bargain and they've been tamed for you! The pet shops sell them for ridiculously high prices.
Degus can bite, and when they do they hold on. Ouch. They can be tamed, but it takes a lot of patience. They wont sit on your lap for a cuddle, they prefer to jump around.
Finally, its good youre getting two because they are very social animals, living happily in groups of over 20 in the wild. Remember if one dies you should really get the other a friend, as they kind of just fade away on their own. Oh and their teeth are meant to be orange, dont worry!
oh and i would say they are the best rodent to own and very amusing!