Flimsy, expensive. Somewhat useful.
These brackets are flimsy, they are impossible to get square and keep square as you screw them into the studs. This means the drywall holes will not be totally square either - especially if they use a router which will push the bracket around as they attempt to "outline" the bracket in the drywall. I have not installed the speakers yet, but I am imagining I will have to make the whole square with a drywall knife when it comes time for me to install them. The only reason I bought these was so that I could very easily show the builder where to pull speaker wire to and to have the drywall people router the holes for me. Otherwise I would have to rely on them to measure out and cut speaker locations and I did not want them to mess it up.
Pros: Useful to designate speaker location for wire pulls and drywall install.
Cons: Flimsy, impossible to get and keep square. Expensive for what you get.