From a brand-new textbook, I give you the paragraph on open-source software.

Open-source software is becoming extremely popular. An open-source software product is developed and maintained by a team of volunteers and may be downloaded free of charge and used by anyone. Widely used open source products include the Linux operating system, the Firefox Web browser, and the Apache Web server. The term open source refers to the availability of the source code to all, unlike most commercial products where only the executable version is sold. Because any user of an open-source product may scrutinize the source code and report faults to the developers, many open-source software products are of high quality. The expected consequence of the public nature of faults in open-source software was formalized by Raymond in The Cathedral and the Bazaar as Linus's Law, named after Linus Torvolds, the creator of Linux [Raymond, 2000]. Linus's Law states that "given enough eyeballs, all bugs are shallow." In other words, if enough individuals scrutinize the source code of an open-source software product, someone should be able to locate that fault and suggest how to fix it. A related principle is "Release early. Release often" [Raymond, 2000]. That is, open-source developers tend to spend less time on testing than closed-source developers, preferring to release a new version of a product virtually as soon as it is finished, leaving much of the responsibility of testing to users.

Whoa. Talk about a disjointed paragraph. I think he says that open-source projects are both unstable (because of fast release cycles and less testing) and of high quality (this is explicitly stated).

Excerpt from Schach, "Object Oriented and Classical Software Engineering", 8th edition, pp. 23-24. As this is a few words out of a 700-page book, I don't suppose I'll have any rights issues.