I have one that looks identical to the one in your link, although mine must be a cheap copy because it was $30 off of ebay.
The idea I had in mind was to set this thing up and forget about it, but that didn't work out.
First the suction cup holder thingy sucks. I cleaned the window and the cup, moistened the cup slightly, but leave it in the sun for any length of time and it falls off.
Anyway, no big deal -- so I thought. I will just stick the damn thing to my dash and it won't fall off.
Well... the falling problem was fixed, but I think the heat killed it. The unit never had to run off of battery power, yet after a day of sitting in a parking lot with the sun on it and it wouldn't turn on again.
I realize that electronics should neither be left stuck to the window or in direct sunlight for a long period of time, but the only way these things will be effective is if they are on every time you drive -- and unless you are a person who never forgets, that means they should be left in place 100% of the time.
I currently have a case opened on ebay trying to get a replacement or refund for my dead unit.