I've been running this filter in a 10 gallon tank for the past two weeks. I set it up to hang on the back of the tank. The 90 degree rubber hoses both had manufacturing defects and I needed to seal them with silicone tape to prevent air from entering. Once that was done and everything was connected, I plugged it in and it was virtually silent. Now, after two weeks, I hear some air seeping in from somewhere and every few minutes I see air bubbles exiting the spray bar. I've taken it apart twice and double checked those rubber 90 degree elbows, but I can't figure out where the air is entering.
The water is still clear with very little maintenance so that is a huge plus over my previous filter. :)

9/10/17 UPDATE
Not sure what is wrong. Darn thing is gurgling and not pumping. I keep putting water into it but it won't go.

Was looking for a canister filter for my 20 gallon tank. This has done a great job at keeping the water clear. My only complaint is that i have to take everything out of the tank to clean the filter. I haven't yet seen a way to remove the canister without taking the spray bar out. This requires me to remove the lid of my tank. Would give it a 5 star if i could figure out how to do that.

I use these on two different tanks. One of them has been running for over a year now with no real problems.
A few things worth mentioning though: If you don't use the spray bar or some slightly restrictive outflow, it will eventually create negative pressure in the canister causing it to suck air. eventually this will make noise and you'll have to open it up and dump more water into it to shut it up. It took me a LONG time to figure this out. I fixed it by adding a valve inline on the output, this was easy to to and added variable output.
Also, I took out the carbon filter and replaced it with a fine sponge. Great Filter- My go-to now for 20 gal and smaller.

Quiet. Efficient. Changing the filters/carbon is easy.

I recommend using purigen instead of carbon in the lower level above the sponge. You can buy mesh small bags and fill with 250ml of purigen which fills nicely horizontally. Then add biomax + prefilter rings in the top level.

You'll most likely want to replace the outflow/inflow pipes since the plastic garbage that Finnex provides you will stick out like a sore thumb. I went with Lily pipes and they look amazing. You can find larger tubing at home depot if needed. To clean any inflow/outflow pipes, buy some long filter brushes (amazon or local fish store) to clean them once a month, it's easy. Protip: if your plastic airline tubing isn't big enough, boil water and let the end of the tube sit in it for a minute or so. It'll get more softer and using a spoon or fork you should be able to easily increase the diameter and then put over your pipes. You'd be surprised how much bigger they get once soft.

I have four tanks. One 29 gallon with fluval 405 and three 20 gallon tanks with Aqueon QuietFlow 20. Fluval 405 perform so well that I only need to add water and did water change every six months. However, it was a nightmare with three 20 gallon tanks, that I have to do 20% water change every 3 days to a week. I try one of this Finnex PX-360 earlier this year and buy two more after three months of testing.

PRO:
1. Light weight and compact
2. Without active carbon/sponge, flow rate are pretty consistent for three month.
3. Cheap as a canister filter.
4. Easy to clean.
5. Quiet
6. Easy to hand on the back or side of tank. (Make sure have enough space, of course)
CON:
1. Instruction for assembly are horrible. Make sure you double check with minor leak after you first assemble. Any tiny leak indicate using the wrong parts.
2. With active carbon/sponge, flow rate slows down after one month of use in heavily planted tank.