I actually just purchased one of those boards for a separate project, but I have been quite happy with it and plan on replacing my atom with one soon in the car. One thing to keep in mind, definently use the included CPU fan. I know it says fanless, but the CPU runs near 50C under moderate load without the fan, and that's inside where the ambient is low. I would definitely get a case though. I've run without a case before, and I always had audio and video noise issues, which a case has solved. Also, with a case you can use directed airflow to help cool components.
That, and a case makes for a much cleaner looking install.