I think it's great as a home base but would never ever shut him up in it. There is no where near enough floor room for him to move with ease. As a minimum, it should be four times the length of him stretched out.
The house rabbit society recommends at least 8sq ft of cage space coupled with 24 sq ft of exercise space for at least 5 hours a day. Most UK sites (and I actually agree with this over the HRS) suggest 12 sq ft of cage space and at least a 24sq ft pen attached permanently - in other words access to 36 sq ft 24/7.
The little levels are great though, bunnies love to jump and explore.