Folding foregrips: useful or novelty?

[Autopistola]

And do they serve any function while folded? I imagine it would feel funky to grip it horizontally.

 

[mcwjr13]

I learned that vertical foregrips are more of a reference point than a full hand grip. One of the things that is nice about a "static" grip is that it still allows you to use your fore end if necessary. by using a folding grip you are minimizing the space on the rifle that you can maintain solid contact with. Just what I was taught.