I agree that the idea of returning an app within 24 hours sounds good, but I would think developers would not be happy with that. Especially of items that are short time to live (games, magazines, books, etc). If I wanted to play Iron Man 2 for the three hours (as someone posted it took them earlier in the thread), then I could download it this evening.... play it straight through.... then return it later tonight. Or buy a single book app before leaving on a long flight, and return it at the end of the flight. I can think of a bunch of apps that I have purchased or DLed free that would fall into this category. Though I would be more likely to purchase OmniGraffle ($50) if I knew I could return it after 24 hour trial period. Right now the screenshots and reviews are not enough to convince me that this would be a helpful tool for me.
I am usually willing to pay $1 for a game that I can get a few hours out of, without worrying about returning it. I even don't have a problem spending $5 or $10 for an app that will get me several hours of entertainment (still cheaper than going to a movie). But I am more selective at this level, because I want to make sure that the item will at least meet that threshold. In those cases, I read the most critical reviews (either on the app store or through online reviews), which can give me an idea of the cons of a particular app. -- but I ignore the aggregate star ratings, as they have issues:
1. As will soon be addressed, deleting apps from the iDevice prompts for a review, so these are usually people unhappy with an app.
2. Scan the text reviews and there are many one-star reviews which have written comments of "great app", "must buy" and similar positive statements.
3. Some unscrupulous developers populate their ratings with 5 stars.
4. Over time, buyers are more likely to be the target audience and will slant the ratings toward others with similar interest/likes and dislikes.
In the end I believe it should be caveat emptor. With refunds reserved for the most extreme cases where descriptions were misleading, problems extreme or other like issues.