Pros: saves some water
Cons: possible injury and death from potential release of toxic fumes
Upon first inspection of the Aqus it seemed to be fairly well thought out. There are a lot of parts that are specialty parts that have been built overseas. During the installation I encountered problems with the rocker device that fits inside the toilet tank. I called Water Saver Tech and got Mark Saunders (the inventor) on the line. After discribing the illfitting part to him, he told me that I probably got ahold of some old stock and promptly sent me a newly designed rocker assembly. A week later, after recieving the new part and assebling the unit I can say that it worked. (sort of). There are electrical points that go inside the toilet tank that are exposed to moisture. These points activate the pump when the water level drops in the toilet tank. They will need regular attention. This design error is exaserbated by the chlorine in the water that causes most metal parts to corrode quickly. This coats the points and causes them to not make a good contact.
Secondly, the only way that the toilet bowl can fill is if that water comes from the fresh water fill of the toilet. So you are only really saving about 3/4 of a gallon per flush. The fresh water going into the bowl gives the impression that the water entering the tank is fairly clean, but it's really pretty funky because there is virtually no filtration of the water coming from the sink. This means that your toilet flapper is going to need to be cleaned about once a week.
The biggest design flaw in this product is the use of 3" chlorine tablets placed in the drain line to disenfect the sink water as it goes to the storage tank. When the water passes over the chlorine tablets it creates chlorine gas. This chlorine gas comes up through the drain pipe and stings your nostrels pretty good. Since there is no sink trap between the sink and the tank there is nothing to keep the gas from escaping back into the bathroom. That isn't the biggest danger though. The biggest danger is if someone is cleaning the bathroom and inadvertantly pours a cleaner containing a significant amount of ammonia down the sink. Guess what? CHLOROFORM GAS!!! For those of you that aren't aware of household chemical rules 101, Don't mix chlorine and ammonia, this is what happens. Chlorofom gas is created from the mixture of chlorine bleach and household ammonia. If you inhale modest amounts of chloroform gas you will be rendered unconscious and your breathing passeges will be permanently damaged. If you remain in the area you could die, but don't ever sign up for another marathon race.
I don't want to harp on this too much, but the swimming pool chlorine that is sent with this product is designed to be totally submerged under water. i.e. swimming pool chlorine. From what I have read in the EPA regulations for hazardous materials, there are heavy fines and imprisonment for using this type of chlorine for anything other than what it is designed for. (swimming pools). This has to do with the fact that when this product is not totally submerged, it creates large amounts of gas that are intended to be entrained in water, not breathed.
The product is however usefull if you don't follow the instructions with the chlorine. You will have to pour something like peroxide down the sink every couple of days to kill the lively bacteria and odor that go along with them.