Very useful.  The 3 different magnifications allow for wide views & detailed small areas.  Natural lighting shows what others will see.  The fact that the sides close both protects the mirrors & keeps it compact.  I would have preferred that it use household current rather than USB, but it also works with AA batteries, so there are options.  The power-on button is a little hard to find each time, but brightness is easy to adjust.  It has weight so is stable.  Battery power also makes it easily mobile.