I've been using one since December now, though I haven't done as much shooting with it as I would like. The polymer Grippod is 7oz. and is an excellent vertical grip. It is rock-solid on the rail, width-adjustable to allow for some out-of-spec rails, and you can take it on and off without having to dismount everything, remove covers, etc.
It fills the hand good, kind of like the TD; but not quite as much as the CQD. I also run my thumbs on the weakside of the gun and the knob that attaches the handle is perfectly placed to rest my thumb. As a vert. grip, I think it is top notch.
As a bipod, it isn't as good as a dedicated bipod; but it is definitely a lot lighter and better than the magazine as monopod technique. The polymer bipod has enough flex you can track side to side a little. The big issue though is that unless you like to run your VFG far forward, the grip is usually not in a great location to provide good bipod stability. If you are like me though and like to "drive" the gun, then it is a pretty nice package.
After all, how else can you get a 65 lumen 6v light, a VFG, and a bipod for less than 13oz?