I have seen that one around a lot and have two problems with it. First, it doesnt remove copper or heavy metals, just organics. If you're going fish only, copper is OK, but if you ever want to have inverts or corals, copper = bad. It can infect your seals longterm and make the tank permanantly a no-coral environment.
Second, that unit treats on average 100 gallons of water for $35 before the filter gets used up and needs replacing. In contrast, my $80 RO unit has allready made me probably close to 400 gallons of water and I haven't replaced a single piece to it yet. Furthermore, it made tons of water for someone else before I even owned it. WAY more cost-effective. Head over to Ebay and grab one or better yet, purchase one used like I did, it really is a good investment.