This is the original Drinkwell 50 oz. fountain. Unit consists of a bowl (that can be used by pets whether or not power is applied,) and upper housing that holds the charcoal filter and dispenses the fountain flow, lid, filter (1 supplied) and pump with AC adapter. When operating, the pump should always be submersed. If operated dry, damage may occur. When set up and operating, the water is pumped into the housing from the intake in the bowl and up to the spout, a few inches above the splash ramp and then back into the bowl. It's a low voltage (12V) pump and there's no chance of shock hazard.We have 4 cats and 2 small dogs. We've only had the fountain one week. All of the animals drink regularly from it. One of our cats was obsessed with drinking from the kitchen faucet. She has now taken to drinking from the fountain, so hopefully this will keep her off the counter. The other pets just lap up the water in the bowl. I suspect that it tastes better since the water constantly passes through the filter. With only a 50 oz. capacity, we keep it topped off a couple of times a day. At our rate of usage, I wouldn't expect the supply to last much over a day before running dry. The pets seem to like the fresher tasting water now that is constantly being filtered. (If I were sharing a water glass with 5 others, I'd at least want it filtered too.)The unit does not have any rubber feet and sitting on the hard floor makes a vibrating sound. I placed a rubber mat (actually a large mouse pad flipped over) underneath and that eliminates the sound. The unit itself is very quiet, but the vibrations on a hard surface can cause quite a racket unless there is some padding. According to the manual, it uses 2W of electricity. I metered it and found it uses 6W --not bad for a small motor that runs continuously.Cleaning. The manual recommends cleaning once a week. This is something that you should do with your pet's water bowl anyway, but this is a little more complicated than a simple bowl. A DC plug is in the middle of the cord that lets you disconnect the power without messing with the AC adapter. That makes it easier to take the unit over to the sink for cleaning. The housing and bowl can be easily rinsed off. The manual also recommends cleaning the pump every 2 weeks. This is a little bit of a chore. The pump can be pried out (it's on suction cups in the basin) and squeezed open. The squeeze points are not marked but once you get the hang of it, you should have no trouble taking it apart. Take the faceplate and intake plate off, remove the impeller and rinse thoroughly. The instructions are fairly complete. The entire process should take about 5 minutes once you get the hang of it.I suspect that most of the complaints regarding this are when the owners (1) let the unit run dry, (2) don't put padding under the unit to reduce vibration or (3) don't regularly clean the unit.My only issue is with the constant need to replace the filter. The basic design seems to indicate that the system could be used without the filter without harming it. I have thought about just filling the bowl with filtered water and forgetting the charcoal filter, but the pets seem to like the water more with it constantly filtered. Yes, it is more expensive and a little more work keeping it clean, but the little critters seem to love it.