I am trying to replace a faucet installed on a small bathroom vanity, and
the locknuts holding the faucet in place are very difficult to reach.

For anyone who has worked underneath sinks and replaced faucets, it is
usually tight quarters and hard to reach. It is especially hard to hold a
basin wrench or other tool in just the right position in order to apply
torque.

I have seen ads for a device called the Basin Buddy which is a patented,
supposedly universal basin nut wrench which claims to make the job much
easier:

http://www.wal-rich.com/BasinBuddyPage.pdf

Does anybody here have an opinion about this product or any other better
method of removing and tightening these locknuts?

Many thanks.