I ran a Dragonstar Campaign titled "The Last Emperor" for about 9 months. It started as a short between-game thing, which got expanded. It worked and the players had a lot of fun playing: merchant trades of shady goods, demon hunting, evil half dragon lead secret project cleanup teams, and exploding stars. The setting is a blast.
On the downside, the system feels patched together, as the modern weapons vastly overshadow the combat abilities of spell casters until high level, and the odd effects of the increasing hit points. My group aren't the biggest D20 fans and I heard many complains about how poorly the system handled. A group more comfortable with the D20 system and willing to work through the system holes it should work fine however.