We were looking for a mid sleeper bed for our son, then aged 6. We visited so many shops trying out various different mid sleepers, but couldn't find "the one". Either they felt too rickety, or the storage underneath was poor quality, or not the type of storage we wanted.
Finally, we visited Glasswells, a large local furniture store, and discovered the Stompa range.
It was expensive, but the bed is solid pine, painted white. The cupboards under are good quality and flexible - you can have various combinations of doors, and I believe they also sell a pull out desk. The shelves are fab- we have a long shelf at the foot of the bed, and a short shelf by the side up at the head end. the bed is extremely easy to assemble, the cupboards take slightly longer as they are a bit more fiddly but still straightforward.
The stompa mattress is also very comfortable. We paid for the deluxe one, and it was worth the extra money as it feels a really good quality mattress and will last.
The bed/mattress are continental sized. We bought a good quality fitted waterproof mattress protector, which was quite pricey, but the sheets you can pick up very cheaply in Ikea.
Overall, we have had the bed for a year now, and both we, and our son are still delighted with it!