We just bought this bed for our very petite 4-yr-old daughter. My son has a similar bed, and she wanted one of her own. It’s a great size for her, abs bit so high off the ground that I’m fearful that she’ll fall out. We’ve only got a mattress on it, no box spring so the rails can come up high enough to provide some protection there. 
It was fairly easy to put together. I did it by myself in just over an hour. All materials arrived in great shape, with all of the parts. 
I do wish there were more slats to support the mattress, however. There were only eight, which isn’t enough to position them across the base of the bed with appropriate spacing. I’ll need to get some more from the hardware store to make sure there’s enough support for the mattress across the whole span of the mattress.