I was looking at that strobe when I first started shopping for one. I came across an overwhelming amount of people that were saying that it is very easy to flood and the output is not that great. All around I was seeing recomendations to hold off, save up more money and get something better, starting at the Ikelite DS-51 (w/ EV adapter if it needs to be triggered optically), Sea & Sea YS-110, or the Inon D2000. Anytheing less would be a disappointment in the long run.
I ended up staying away from it and while saving up for something better, I stumbled across Sea & Sea's closeout page (
LINK) where I found a YS-60 kit, complete with strobe, tray and a simple arm (not that great, but at least as good as the one that comes with the GFlash) for $135. This strobe does not have an optical slave mode, so I got a Heinrichs-Weikamp DA2 for $130 (
link - make sure to get this one for the YS-60 on the closeout page, not the one with the Sea & Sea plug since the YS-60 on the closeout is the 5-pin N-type) which was basically designed with the YS-50 and YS-60 in mind in order to shoot them as a slave flash triggered by the camera's flash. The YS-60 is an older (less modern) version of the YS-110 with slightly less output and lower specs, but is a very respectable setup that can be used later to compliment a more powerful strobe should I want to upgrade (at least that's the way I see it). I've only taken it in the water a couple of times now and am still struggling with strobe placement (thanks in part to limited adjustibility of the arm) and getting the hang of shooting with one in the green currents down here.
If you can afford them, the DS-51, YS110 or D2000 seem like much less hassle and I see them very highly recommended. If you can, get one of them. But if the budget is too tight, consider the YS-27 (looks like a decent setup and less hassle than mine). Fianlly, consider the setup I got for about the same price as the GFlash.