Nick,
I'm using it and have had no problems with it. Been using it about 6 months now I guess.
I just downloaded it from their web site. I'm not a tech/geek guy so anything beyond that I'm not the guy to talk to.
I will tell you that I rarely, if ever, get any more pop up ads, don't know if that is a function of Mozilla or not, but the download was easy. It seems quick and so far so good.