I've been both a backer AND a fundraiser on Kickstarter.
I was a backer first - I've supported 5 projects personally.
I also had a big hand in the creation and management of both the Impossible Instant Lab and FILM Ferrania fundraising campaigns (and consulted on three others).
I backed another 12-15 more projects through Impossible and FILM Ferrania - all photo-related.
Having been on both sides of the equation, I can say a few things.
As a backer:
• If you simply enjoy supporting arts projects - books, photo essays, films, music - you will find a wide variety of extremely worthy campaigns. Find what you like, support it, share it around, and you'll rarely be disappointed.
• If you consider your backing an investment - in a person or team or company and their ability to deliver products or art or whatever you will want at some point in the future - then you will generally be a very happy Kickstarter.
• If your interest is simply buying products, you will most often be disappointed.
• Every project I've backed, personally or professionally, has delivered - or are still pending with every sign that they will deliver. One is overly delayed, but the founder has been extremely open and honest and communicative and still has my full support.
As a fundraiser:
• It's an enormous amount of work to run a successful campaign.
• Whatever amount of work you estimate it will be, will be wrong by a factor of 2, at best.
• Even if you read the first two points and think you know how much work it will actually be, it will be much much more. I promise.
• Expect to collect only around 80-85% of what you raise - after fees and attrition. Plan accordingly.
• Tell your backers everything you're doing to deliver their rewards as often as you can, and as honestly and openly as you can, even if it's bad news.
• Kickstarter doesn't really have the best or most robust tools to manage the workflow. If you have Excel skills, you will find them useful.
• If you don't already have one, grow a thick skin.
No matter which way you use it, I think Kickstarter is an amazing resource.
The other crowdfunding sites tweak the Kickstarter formula in various ways, but none too drastically. I would expect that most of what I've experienced with Kickstarter would hold true on the other platforms.
I would say that the reason for the "trend" in major film and camera projects using crowdfunding speaks to the difficulty in pursuing traditional financing for these types of companies more than anything else. Also, it also clearly shows the demand that is being otherwise unaddressed.