I have had Rainhandlers on my house since about 1997. I originally found out about them by an article written by the handyman reporter for the Providence Journal who raved about them from a Consumer Reports study on gutters. My eaves were rotten, caused in part by a large tree in the yard towering over my 3 story house. This was the perfect solution. I would not need to clean out the gutters and it appeared that it would work fine.
Now, 18 years later, the Rainhandlers are still doing their job well. I have also installed them on a second home and am about to install them on my 3rd home after experiencing tremendous ice dams this past winter caused by the gutters ruining my walls and ceilings.
I have found that the Rainhandlers do much more than just eliminate leaves from going into gutters. A lot of people (including others that answered this question) missed the point that a gutter collects all of the surface water of the roof from the ridge line down and then channels the water into a corner downspout, exponentially adding to the water concentrating into the ground at that point. With the Rainhandlers, the only additional water landing near the foundation is that rain from the ridge line to the lip of the roof all along the wall. It is not concentrated. Further, since it kicks out the water in a random pattern, it has the effect of adding a little rain.
In the winter, a gutter collects and freezes the water at the roof line. With freezing and thawing and refreezing the ice builds up in the gutter and backs up under the shingles causing an ice dam. If you live in an area that experiences significant snowfall, you have to ask yourself why would you want to create a large longitudinal ice cube on your roof and risk damaging the inside of your house?
The Rainhandler does not collect the water, there is no downspout, they are practically invisible and they are a DIY project for the average homeowner at a small fraction of the cost of gutters. For all of these reasons I love them.
With that said, there are things to know about their uniqueness. If you have roof valleys you need to add a diverter which they sell, so all of the water does not concentrate in the valley. A "doorbrella", which is a right angle piece of aluminum, glues on the roof over the door to keep you dry. Also, in the winter, the Rainhandlers tend to generate large icecycles when the snow thaws and freezes (because the water is melting off and not freezing along the roof).
Check out their website (link attached) and their You Tube videos which do a good job of showing how they work. Again, for me, I have had it with cleaning debris out of gutters and worrying about ice dams and would never put another gutter on my roof. While perhaps not for everyone, for me, I think there is significantly more to like about Rainhandlers than just not cleaning leaves out of gutters.
Source: http://www.rainhandler.com/