The run-down buildings—and frankly, almost the entire city of Havana is unfortunately like this— have to be overlooked. Although these structures are an eyesore, inside many are hidden gems.
The Havana airport is also neglected, has no clubs (yet) and many of the attendants do not speak English. This will probably change as more U.S. flights are added.
For the foreseeable future, the USD is not accepted anywhere, although the process of exchanging the Cuban currency (CUC, which operates at the same exchange rate) is quite easy, and multiple outlets can do this. The best place to exchange is at the airport. It is important to bring far more cash than you anticipate needing because there is absolutely no means of getting more or using credit or debit cards.