It looks like you can adjust the depth of the bed and, therefore, could plant just about anything that doesn't NEED to root deeper than the height of the palette. To change the depth, you just put the horizontal palette lower on the vertical palette.
This still does not address the issue of reaching tall plants when they start fruiting... And combating bugs on leaves that are out of reach...
I guess you could always build a deck around it...but then aren't you defeating the purpose?
The guys in this picture think this is a fabulous idea...but once their garden gets going they will learn the ins and outs of what they are doing and will most likely reengineer their system for next year applying what they have learned.
Very much the same way I learned what I learned over the past few years since I started gardening.