In general I am a fan of Kickstarter and to a lesser amount, GoFundMe. I've backed quite a few things on Kickstarter and been pretty darned pleased with most of them. Where I find myself reluctant to back a product is when it involves slightly complicated production or technology. Particularly if this is the teams first go at a product. They tend to run way past projected delivery, stumble, and the end product isn't always that great.
Where I am rarely disappointed is backing a book. Books are generally pretty straight forward from concept, design, production, and fulfillment. Things fail of course. Sometimes the creator wasn't far enough along in the content creation and when they HAVE to produce they panic and collapse under the pressure.
Never, ever expect the project you fund to deliver on time. It rarely happens. People make plans for their project based on meeting their goal. Lightning strikes and they end up funding 200 or 300% and aren't prepared for the success and struggle to scale up. They offer stretch goals and don't factor in the added time it takes to fulfill those goals. 9 out of 10 times book production appears to be in China. It's just economics. It takes time to get things from there to here. Proofs have to be created, shipped, turned around if problems are found. There are holidays that might unexpectedly delay production. A hurricane might sink your ship. Essentially shit happens, don't freak out if it takes a while to get your reward.
If you do back something, engage with the team. Kickstarter has messaging within the platform. If the team working the project is communicating with you and giving updates, respond. It encourages them and garners you good will and helps keep you informed of what is happening so you don't think they just vanished with your money.