Someone told me there was a demo for the game on GOG but I can't find it. Anybody have a link? Did I miss it on the store page or something?

In a way, the store listing you see IS the demo. It's a preview campaign that is separate from the missions that will end up in the final release. IIRC you will get upgraded to the full version once it's released, but the preview campaign will remain in the goodies section.

*face/palm*

Oh duh. I knew the campaign was a preview but I didn't realize that's what the dude was referring to. I want this game really bad but it's hard to justifying spending the money with so little content.

If you have Bombshell in your library it grants a key to access the Ion Maiden preview as well.