The first one I backed never went into production, no one received any product at all; They only updated a few times and the last update was somewhere near the promised ship date for the backers. Never another update after that and no product ever arrived. Inquiries went unanswered.
Another one I backed showed a lot of drawings/prototypes/videos of the product, ran nearly a year late with no updates. The product did arrive but it was not, in my eyes, even close to what was promised.
The third that burned me was another lost cause. Updates for a while about how the demand was overwhelming and they couldn't find a manufacturer that could produce the numbers in the proposed time frame, then no updates, then no product.
I could chalk it up to bad luck but it honestly left a really bad impression of Kickstarter. Granted, I did not contribute large amounts of money but other backers did and the goals on each were certainly well exceeded...so it wasn't a lack of funding.