I made one a few year back. Was tired of a queen bed in a guest room taking up space that could otherwise be my office.
The kit was a piece of cake. I modified the style a bit, to add a fold out desk under the bed frame, and added side cabinets.
The hardest thing was a design flaw i made in the cabinets. I had hoped to reuse some cabinet doors i had from an old entertainment center, but couldn't match the stain, and couldn't find a router bit that matched the profile. So i shifted gears and went to full inset shaker doors, without a face frame on the cabinet. It was a HUGE pain to get the gaps even.
Still one of the better projects ive done, and we're pleased with the results, and having a guest bed that s just as comfortable as a regular bed, but not taking up around 40 sqft year round, for the 5ish nights a year my parents come visit.