It looks great! It would be sturdy, though I know it doesn't look like it.
I made a cage for each of my buns out of the same thing, except I attached the panels with zip ties (really cheap), and used pegboard as flooring (rough side up, also very cheap). The good thing about building it yourself is that you can construct it any way you want. You can make it whatever size you want, make the additional levels whatever size and shape you want, you can even build them stairs going from top to bottom on the outside of the cage if you want! I love the creativity doing it myself allowed.
The cage you have pictured is really nice, but doing it yourself is much cheaper and isn't that difficult to do.
You can check out the thread about cage pictures to get some good ideas on how different members designed theirs at:
http://rabbitsonline.net/view_topic.php?id=1931&forum_id=1&page=1
You can also check out this thread, posted by TrixieRabbit, about how she made hers:
http://rabbitsonline.net/view_topic.php?id=12961&forum_id=6&jump_to=203230#p203230
I hope all that helps! It's really fun, and much cheaper, though the cage you picture is quite nice, too!
Let us know what you decide to do, and be sure to post a picture of the cage in the cage photo blog!
P.S. Welcome to the forum!! Be sure to also post pictures of your bunny.