I have found the clamp to be really handy, though I do have a couple small notes on its design.
If your doing video work it can clamp onto your tripod and allow you to use your phone to hold your script without you looking away from the camera.
The phone mount being detachable and using a basic camera mount means you can also simply use it to attach to you camera itself and serve as a micro tripod that just needs to somewhere to clamp.
The phone holder can also be attached to a regular tripod head to allow you to use your phone there too (kind of a small bonus that you wont have to buy a phone adapter, as you can see in the picture attached the phone mount having a cold shoe is great for little detachable lights or such too.
The screws all seem very durable and well made, I would have no worries about attaching my dslr to this. (There is one screw I have noted a small issue with.)

Cons.
The main screw for the clamp, the thumbscrew is reverse threaded to the main body, not attached by its own screw or adhesive, as such I found it came loose when I first tightened the clamp, easy fix, I just ran some super glue into the threads and put it back on, and let the company know. Very odd design flaw but not the end of the world.
It would be nice it it also had a small tabletop mount, the clamp does not easily attach to flat surfaces so it would be good if it had something for that.

Conclusion.
I really like this little clamp, I intend to carry it when I cant use my big tripod for wildlife shoots and if I start getting into videos where im talking into the camera.