Call of Duty 4 is something of an odd game. While it has the gloss a modern game the mechanics are the same as they were in the very first title. As the demo goes it can be narrowed down to a few very simple conclusions.
The main issue is an infinite amount of enemy spawns. A constant line of more and more keep on coming until you decide to push through and that’s when suddenly you have taken them all out. Its a serious flaw and ruins the enjoyment. The other matter is the demo length. It does allow you about 10-15 minutes of play but unless you have a good amount of bandwidth its not really worth downloading the large file and there is very little replay value.
Is the demo worth trying? In short, yes. If you are looking for a first person shooter giving the usual WWII shooter style but against a modern backdrop its for you. If on the other side you are after something new its not what you are looking for.
Remember, this should not be considered a review of the full game just an opinion on the PC demo.