This is a fantastic unit for a number of reasons but you already know most of them or you wouldn't be looking here. The self cleaning filters remove impurities in the water and dispenses crisp clean water that tastes just like the bottled stuff we all foolishly pay for in vending machines. This is to say nothing of spilling three gallons of water as you invert one of those massive jugs.

Let's focus on your biggest concern.

Installation took about an hour and a half, though most of the holdup was at my end, not theirs.  If everything had gone right and the cat hadn't felt the need to be a part of the job, it could be completed more quickly.  My skill level is such that I can replace a toilet or faucet but I am not a plumber. Fortunately I was enough. The hardest part is access under the sink. I'm a large guy and with the drain pipes right there, they got in the way. But it was cumbersome and not confusing.

They include an adapter that connects right above the shut off valve under the sink.  All you need is a wrench and some plumbers tape.  Shut the water off, remove the hose going to faucet, screw in the adapter, connect it back to the faucet hose, connect the water feed line, drill a hole and feed the hose through. Take a breather and stretch your legs, distract the cat. Then turn off the cooler's water there is a shut off on the adapter. Now turn the main water back on.  If you are lucky there will no leaks.  I had none.

You have to flush the filter for 5 minutes before use and it comes with a lovely tool to do this.  The connection to it is a nice compression fitting, push the hose in and gently pull back.  Presto!  To remove it after the flush job simply push in the blue ring and pull the hose out. I am an inept artist type and I promise this was easy. Though in truth, the directions I've given here are more clear and less frustrating than the pamphlet included.

The convenient aspect about the flush is that it allows you to see how the filter will screw into the unit once you are done.   And that is what you'll do next.

They make it easy by having the connection point flip up to make it easy to access. Double check that all the arrows show the the water flow is correct.
The connection point from the hose to the unit is just another "Push in the hole, then gently pull".

Look for a grey ring, (like the blue one on the filter). The ring needs to be pushed in around the input line for removal- it will make perfect sense when you're looking at it. This locks the hose in place.

Homestretch now: power it up and you'll have cool and hot water in just a few minutes. There is even a night light so midnight thirst doesn't require a blinding overhead.
 
I noticed a few things worth mentioning.
There is a slight bulge on the top of the unit as if something were pushing against it.  I'm not sure if this is a defect or just the design. You can see a slight color change where it's pushing up and feel the bulge. it's slight and doesn't seem to affect operation.

Perhaps someone with more tech skills than I could make a YouTube installation tutorial. Without the cat.

The water temperatures are hot 175°F and cold is 47°F. 

The design includes a handle on the back to make moving the unit easier.

Within a week you'll wonder why you didn't do this long ago.

So, this water cooler does the basic of what I want it to do -- provide fresh, good tasting water that's cooled or heated to the temperature of my liking. It was easy to set up and maintain. What I ESPECIALLY liked is that the Avalon filters are certified to NSF standards 42 AND 53 and is filtering out a lot more particulate and contaminants than a lot of the refrigerator dispenser filters available on Amazon -- which are often certified only to NSF 42. The downside is that these filters are pricey. If you are changing it every six months, expect to spend about $150 a year on filters alone. This is a lot more expensive than the Culligan under the sink water filter system I am currently using, in which I am using the most premium (and costliest) Culligan filter and spending almost half as much as the Avalon filters per year. But be aware that if you're using it in a home setting, rather than at an office or gym, you will probably be able to wait much longer than six months to change the filter as each filter is rated for 1500 gallons. (In contrast, my Culligan filter is only rated to 500 gallons.)

I prefer using the Culligan for filling up my pots with water for cooking rice and soups (the Culligan dispenses the water more quickly than this Avalon system and it's easier to fill the pots at the sink). But I prefer using the Avalon water cooler for filling my glasses or water bottles. It gets the water the perfect drinking temperature and tastes fantastic. The heated water is also a bonus and part of the reason I wanted the Avalon cooler--my countertop hot water urn just died after 4 years' of use and now the Avalon hot water dispenser allows me to reclaim the counter space and without giving up the convenience of having instant hot water to make tea throughout the day. My kids also prefer to use this Avalon water dispenser due to ease of use and easier access (for their height).

I have one bit of concern though. All the listings I've found for the Avalon water filter replacements seem to say that they are compatible with the bottleless water coolers purchased before March 2018. This implies that the water filter designs are about to change? If that is the case, then purchasing this water cooler now would mean that it would be obsolete in a few years as they phase out the old water filter design, so buyer beware.

Great product by Avalon

Perfect for my home gym! Super cold water, and Hot water is almost boiling! Overall amazing product!

I bought this for my medical office because I was tired of paying Crystal Springs $200.00 a month. Love this water cooler! Machine is quiet and sleak.