I like open source stuff, for a variety of reasons. I like the philosophy behind it, and I like the idea of many eyes and many hands working together to create better things. While I do understand that there are situations where open source is not appropriate, such as with the proprietary things I work on in my day job, I also believe that there are many cases where open source is not only appropriate, but necessary.
Software is a case in point for open source. With open source software there is less likelihood that someone will slip a nefarious backdoor into an application, and the overall “attack surface” (as the security folks call it) is much smaller than with closed applications. Free open-source software (FOSS) also has the benefit of multiple eyes reviewing it, finding bugs, suggesting (or creating) improvements, and serving as inspiration for other projects. But there are two problems with open-source software that I believe will be fatal in the long run: The documentation sucks, and the attitude of some of the people who write FOSS does nothing to help the cause. I believe that these two things are closely related.