Obviously, I'm not going to guarantee that the people who put up the project won't run off and cheat you... I'm not omniscient, nor am I a god.
From what I've seen of Kickstarter, most of the creators who start campaigns on Kickstarter have very solid goals in mind and update you regularly on their progress so you know they're still working on it. A lot of times, the deadline is pretty far ahead of when they're asking for funding. For example, a project might not reach fruition or deliver tangible rewards to your doorstep for months, or over a year.
You have to read the descriptions of the rewards/incentives to see if you actually get "a product," but yes, if you fund these campaigns, you do get something in return for your support.