I think the tanks look great and very unique.
I have gravel in two of my tanks, and sand in the other two. After working with the sand, I plan on making the switch in the other two tanks when I get time. I really like the look of sand and gravel is too difficult to keep clean.
I haven't tried sand yet, what would be involved with putting sand in the tank?
If they are fake plants then they might be safe. If they are real, I bet my house on them lasting no longer than a few weeks at the most before they start rotting.
They are very clearly not real just based on the look...not to mention that it was already stated that they are not real plants.