From my experience, demo's usually are not a great representative/indicative of the final product. More often than not they do more harm than good, so I steer clear from them and use my own methods (long process, but has not failed me....other than Brink). Unless the demo is a good one?
The demo is the first Island on the main game and you get to play up to the first teleporter which brings you to another Island in the same level.
It's the final product so it is a good indication.