“The social scientists are right to say that we should be a little sceptical of greatness, and that we should always look in the next room. Great art and mediocrity can get confused, even by experts. But that’s why we need to see, and read, as much as we can. The more we’re exposed to the good and the bad, the better we are at telling the difference. The eclecticists have it.”
The Mona Lisa was an obscure piece of art before it was stolen. It benefitted from the “cumulative advantage” of being popular. So is it actually any good? I guess it depends on how susceptible you are to popularity and how well you understand art.