My sister has a set, bought from Tentworld late last year when they had them on sale for $299. We've borrowed them quite a few times, and will probably grab our own set soon. Great in the camper, but also really handy at home for kiddie sleepovers.
It does look like a lot of pieces, but they assemble surprisingly quickly. For use in a camper, we've always just taken the ends off and left the stretchers & sides assembled on top of the main bed. Takes only a few minutes from there to have it all set up.
They're an incredibly solid unit. I've used the top bunk by myself, nobody on the bottom, and had no concerns about stability. They're also quite spacious - I'm 6 foot, 110kg, and there's plenty of length and width for me to get comfy. Easy to get in and out of, too, with no support bars through the middle of the beds.
Probably overkill for a couple of little kids, but a good unit if you want sturdy bunks that adults can use as well.
