I have a good friend who's husband works in the oil industry out of state. When she and the kids are there, all 5 of them live in an RV and have a mini PNP because a regular one is just way too big. At home, she's got a regular crib and plenty of room. She's the only person I've ever know to have actually needed one, but it's about the same size as a standard size rolling-carry-on suitcase. Pretty much just enough to fit the baby lengthwise, up to 30" or so, and very narrow.
Mini cribs are the same size as a pack n play. We have one and I feel DD outgrew it way too fast. She still fits in it but she moves around a lot and just looks uncomfortable so I don't even use it anymore. We're space challenged at home but I wish I'd bought her the bigger crib.
We had one in our 1 br apartment in lieu of a bassine. I didn't know how quick our house would sell and most basinets had a weight limit of 15 lbs. The mini crib was 50. When it would have been time to transition him to the big crib, it timed perfectly with us buying our house. He got his own room and a big boy crib. I'm due in Sept with our second and he/she will be in the mini crib until ds goes into a car bed. Then the new lo will take the big crib we have. It worked for us.
Re: what's up with "mini" cribs? what's the point?