I've tried it and I'm still not impressed. I have/had all the other 'Headshops' too, none of them do what they claim they will and you still won't end up with a replica of who you wanted to create, in fact most of the time I'd be amazed if you even get anything that looks close to who you wanted to create.
I also have and still use it a lot, 'FaceGen' and although it's much more basic and you still have to manually fiddle around with your figure to get it where you want it, I find it gives a far better base to start from and in some instances I've even been very pleased with the likeness it has given me to start with. FaceGen pretty much needs a very good, clear picture to work from if you hope to get anything out of it, Headshop, I find is just a lot of hardwork for a very poor result.
By the way, did you know you can use it as a stand alone program ? I've taken it out of my Daz Studio and just placed it in a folder on the desktop and it still works from there, I haven't got around to sending any results back into Daz from here yet so I don't know if it will be any better or worse.