We use them a lot to measure duct length, room size, pipe length and so forth, but they can be somewhat annoying because you have to have a kind of dimly lit target. Basements are perfect, but a bright room with direct sunlight or outside during the day, no go. I have a Bosch and a cheap Craftsman and they both work fine, down to the 1/16" i believe, so plenty accurate. Some people say carry a black piece of paper or a board painted black for bright conditions, but I'd just as soon carry a tape.
One thing I did use it for that was invaluable, was measuring the attic of a church that was 65' long for wire and ductwork installation and it was invaluable. I would have had to traverse the attic several times to get the measurements. With a laser it took maybe 15 min, and all I had to do was stick my head thru a access hole.