I agree, it's not worth the money IMO. I have to say that I've never had one of these things myself - do you know whether it would be dangerous to have very small fish in there - would the filter system suck them up (seem to recall a diagram with a tube-like thing in the middle that might be a problem).
If they are safe, you can do a tiny planted community. No bottom-dwellers though and, if you want a decent number of fish, you can only get realy, realy small species - what do you think of 5-6 spotted rasbora, a trio of endler's or mosquito fish or maybe a honey gourami or some sparkling gouramies? Any combination would work as long as you stick to the right ratios, don't over-crowd the gouramies and make sure the rasboras are in a small school.
If you can't go with these, maybe get a trio of platies and a betta or some guppies (not with a betta). A dwarf gourami would also work instead of the betta.
There are also some killis you could do. Try breeding a pair of american-flag fish in there for example (plant heavily though - either live or fake doesn't matter).
As I said before though, I'm not too familiar with the workings of this contraption so be careful of your choices. Is there no chance of replacing the substrate with something less sharp? Then you could have pygmy cories, small loaches, otos (may be possible anyway as they tend to stick to the glass/plants) etc. You could even have shell-dwellers or a badis. There's small gobies (both freshwater and brackish) that would work too but I wouldn't feel comfortable putting them in a tank with such sharp substrate. Also, I don't know how well yu could grow plants in that gravel.