I have to agree with others that say that their UB is awesome (experimenting with Songhai now). Basically, every city can build a mini-Stonehenge? Sign me up! +5 Culture, no maintenance, 2 artist slots. . . What's not to like. The UB alone can be used to leverage so many different strategies - it is especially handy for picking up the late game Social Policy trees, since you have to wait until Philosophy. The UB alone, more than negates the +30% increase that each city adds to Policy costs. And extra gold. . . .