I expected this to be a cheaply manufactured piece of rubbish, but I was buying it for my 9 year old to strap a 5 year old device to his bike so I didn't really care. But it's actually pretty good! It's sturdy, made of solid plastic, comes with lots of adjustable padding for both the clamp and the phone holder. It locks in place really well, doesn't rattle around and attaches firmly.
I would be comfortable putting an expensive phone in this holder.