I have the Bessey variation of the clamps you're inquiring about. While I 100% agree with the above posters that these are not the go-to clamp for anything needing serious clampling force, I do find them quite useful nonetheless.
They are great for lighter clampling pressures for non-loadbearing members, much like pinning trim, etc., to hold it in place for the glue to set. They're also great for small items that are too small for a full-size bar clamp (and you can line up a bunch of these clamps next to one another for greater clamping pressures). They also adapt nicely to moderate curved and angled pieces since the jaw pads are articulated.
I also find them very handy for holding everything in place while I break out my bar clamps and tightly clamp everything down while the glue sets. Since these clamps can be operated with a single hand, your other hand is conveniently free to hold the pieces in alignment.