I like a short epilogue as long as the book's central story has already wrapped up nicely. In that case it's a bonus that gives the curious reader a look at the future without bloating the plot structure of the main text.
I just finished Philip K. Dick's Flow My Tears, The Policeman Said which gives a quick summary of where the characters and institutions end up in a few years; it's important for reinforcing the book's social commentary while maintaining the power of the central story by keeping it streamlined.