Also, the game demos should maybe just give you the first few levels to try. If you were to get your hands on something like Super Monkey Ball for a day trial, they'd make no money because you'd be able to beat it.
I agree with those who agree that you shouldn't be forced to buy an application to post a rating type message to let others know about other similar products that work well, but what if they were simply marked or categorized? That way you'd know if the person has used the software or if they've simply posted about something else.
I didn't read all of the comments here but will say what I think.
What about having all the applications run in full version for a specified period like 2-3 days unless the developer has a trial or lite version?
I agree with the poster above about the ratings and that I myself won't buy anything unless I read the reviews. So allowing any one to post a review if they bought it and allow people to post comments about other applications available so every consumer can make an informed decision before they buy.
The way the App Store is setup up now is like the candy/magazine aisle as you go pay for your groceries, it's all a impulse buying decision. You can't really make an informed decision about most if not all applications.