They are alright, definitely better than worklights. Worklights tend to give off a nasty yellow light, the bulbs that come with the impacts are 3200k, so that's a plus. A down side is that these lights offer absolutely no control. You will just get a flood of light, with no way to focus it, but again, better than a worklight. Also, one of these 500 watt bulbs will give you more coverage and output than a 1,000 watt worklight will, so that's also a plus.
Most people just use worklights and blast the spot with light, and that
looks bad. Smaller lights are the way to go, you can get a more
dynamic image this way. Blasting a rail with 3 1,000 watt worklights
is not lighting. If you just want to light a spot to ride, then
whatever, use worklights.
I'd say go for it. If you want to step up your filming game for little money, pick up a set. You'll also want some sand bags to put on the stands so you don't get any lights tipping over. If it's not bagged, it will happen eventually. Also, buy a bunch of extra bulbs, they will break.
hope this helps
