Recently I've taken to downloading the demo for any upcoming XBox game that I am even vaguely considering purchasing. I would now go so far to say that I wont buy any game unless I've played the demo.
The try before you buy approach is a good one but I cant help feeling that the demos that I have tried recently are letting the game studios and the gamers down.
While I appreciate that the publishers demand a demo be released by a certain date: "not representative of final gameplay" while maybe true, is really not a good way to release your product to the general populace. If it is rubbish now why will it be any better in 2 or 3 months time when its finally released? I'm not going to name any titles here but my gaming friends and myself have been completely put off by a lot of the so called "big releases" recently purely because their demos were so rubbish.
There are of course some exceptions. Overlord - a game I probably wouldn't have looked at in the local shop - has a great demo. As a result I purchased it (still busy playing the expansion pack).
Last night I downloaded "Too Human" demo. Pretty good stuff, helpful on screen popups telling you how to control your character. I wish other studios would realize there is no manual in a demo and some control layouts are not immediately obvious. Too Human demo goes on for quite a while and gives you a good feeling of the in game menu systems / combat system etc. It certainly has me keen to purchase it.
So if you are making a demo here are bv2's guidelines (ok suggestions...):
Try and keep it small. 1GB is pretty much all I'm prepared to download (Too Human was slightly bigger)
Lots of handy popups on how to play, especially the controls - maybe even a commentary on top of the action (Overlord does this well in the demo)
Limit the cut scenes - we are trying to get a feeling of the game play not what your artists can shoe-horn into the download. OR at least limit them to a small percentage of the demo time.
If you feel the need to include "may not be representative of final gameplay" anywhere in the demo just STOP and rather make it representative. You will be severely impacting your sales.