We did interior cabins on RCL's Navigator of the Seas and Vision of the Seas and we found it fine. I think it depends on what kind of traveler you are. We're the types where we're rarely in our rooms (just to sleep and freshen up) so we usually don't want to spend a lot of our dough on the accommodations. However, for future cruises, we'll probably try for an interior room that faces the interior centrum area on an RCL ship that has this feature.

Our rooms were obviously small but big enough to have a mini-couch in it. The amount of closet and storage space was fine since the design is very efficient. The washroom was tiny but I'm not sure if it'd be a lot larger in just a oceanview or balcony room (though prob noticeably larger in a suite).

Probably the biggest quirk though is the lack of natural light so you don't really get a good sense of what time it is. It wasn't a make or break issue for us as we just used alarms to wake us up and the rest of the time, it wasn't an issue.