ive used it (not on my current car) and to be honest its pretty good stuff, never left any swirls that i noticed. never used it if the car was too gritty but everyday road grime is gone in seconds. best idea is get some good microfibres, one for applying and another for final buff, and spray on the car rather than the cloth. and start off where you already sprayed so your not rubbing the dry dirt in. sounds and looks like the usual b/s gimmick but does genuinely work well.
Make sure you still use a good quality wax every now and then though as doesnt seem to last as long protection wise. ie water beading.