The only thing I don't like is that post holding up the loft. I think I would extend the loft a bit and make the support a bookshelf like it is on the left side.
I like that the bottom bed's mattress is on the floor 1) easier/less expensive to build; and 2) lower height for top bunk.
Cat crate Bed Creative Pet Furniture Design Ideas
Make this Mid Century Modern Bed Inspired by one from CB2!
Beautiful DIY wood planked built in bunk beds painted in Benjamin Moore White Dove, lots of great step by step photos of construction on blog
Blue Hanging Loft Bed For Kids
The bed pictured is a twin XL over queen with a full size trundle.
DIY Kids Bean Bag Chair (in 30 minutes!) - no fancy sewing skills required! #DIY #playroom