One map (Container city), a couple of different guns, offline only, no customisation, medium only. You pick a character archetype, faction, class and guns from the 4-8 available. Barebones stuff, with some extras to hook people.
I never got ET:QW, because I played the demo and that was enough for me. So putting that much content in one demo is a bad idea. Also, you want a comparatively small file size so it downloads quickly.