The Economist has an excellent article "Open, but not as usual" on the strengths and limitations of open-source software.

However, it is unclear how innovative and sustainable open source can ultimately be. The open-source method has vulnerabilities that must be overcome if it is to live up to its promise. For example, it lacks ways of ensuring quality and it is still working out better ways to handle intellectual property.

But the biggest worry is that the great benefit of the open-source approach is also its great undoing. Its advantage is that anyone can contribute; the drawback is that sometimes just about anyone does. This leaves projects open to abuse, either by well-meaning dilettantes or intentional disrupters. Constant self-policing is required to ensure its quality.