PRO: Open-source software is safer and more reliable.
There is a common misconception that stubbornly prevails, namely that OSS is more prone to failure. In fact it’s quite to the contrary. Any sufficiently complex and modern program will always have bugs, they're an inevitable byproduct of writing software. OSS is more reliable in that it gets reviewed by many developers, users and testers. This means bugs are more likely to be found, and that bug fixes and security updates are fast in coming.
When you calculate the hours of volunteer effort that goes into building open source software, it’s daunting. The work is distributed among many individuals, agencies, not-for-profits, enterprises, and more. Not a single one of them could produce the results alone without enormous expense. And they all contribute their time for free, and distribute the results for free.
CON: No one is obliged to help.
While the open source community is good at responding to issues quickly, no one is legally obliged to do so. That being said, most OSS applications do offer support and maintenance services - at a cost. For instance, if you’re using the open source content management system TYPO3 there are a whole lot of qualified agencies and freelancers you can hire.
Our company - the TYPO3 GmbH - is the commercial arm of TYPO3 and in response to this concern we offer SLAs (service level agreements) to support the TYPO3 core. This warranty covers service due to failed components within a specific time. We also provide further services like Extended Long Term Support (ELTS) and Project Reviews. Our overall goal is to establish 100% accountability.