If you do it right, you get more distance to your punch. A guy that is way shorter than me caught me with one. I didn't think I was in any danger of getting hit, because he was so far away, then BAM! He came flying through the air and caught me!
ive used this a couple of times sparing (probably 5-10 times in 3-4 months of training) and each time as long as i set it up with some good leg kicks it lands probably cleaner then anything else ive ever thrown.
again as long as its used sparingly, you dont want to become someone who uses this a lot, but it is nice to toss at someone who doesnt expect it, you can really get some good power and distance.
Plus its fun to throw and a crowd pleaser, but it isnt something you dont want to throw 3-4 times in a round.
you are propelling yourself off your back leg and thus really getting your whole body into the punch so if anything theres more power to be had from the punch, but like people have said its a surprise attack and you really only have like one or two shots at landing it