Solid fun sim, must buy if you are interested in NASA.
The space tourist adds a challenge to the gameplay, and some humor, but its actually not that far from reality. Russia's been sending tourists up there for years now. If I recall, one of the members of NSync was even going to spend 20 million for some time on the station before the deal fell through. Anyway, it actually is a situation that the real astronauts have to deal with when Russia sends a high paying civilian up to the station.
Responding to earlier criticism about the demo not working, I have not had the same experience, maybe because they worked those bugs out in the end. The game run's great on my computer and I've had no problems with control issues or crashing, though I've used a keyboard and mouse, and don't really know why anyone would try and use a joystick for a building/resource management sim game.
In conclusion, Space Station Sim is a really fun solid sim, and a must buy for NASA fans. You can build and run the International Space Station how you see fit, ranging from how they actually are doing it in really life, all the way to some pretty crazy designs. You have freedom to send Astronauts from different countries, with different skills, to keep it running and doing experiments. There are a couple points that might have used a bit more polish, but overall its a great looking, really fun, novel sim game, that I would recommend to anyone with any interest in the International Space Station.