The case against TypoScript
Typo3 is a longstanding and very popular open source Web CMS. Although written in PHP, Typo3 employs its own declarative configuration language called "TypoScript" for templating. TypoScript's language and syntax are sufficiently complicated to merit an entire book on it. In our research for past several editions of The Web CMS Report, nearly every Typo3 developer or project manager we contacted told us privately they had a love/hate relationship with TypoScript. However, in blogosphere it seems like "love" has been prevailing.
But then I happened across this comment: "I think TypoScript is a completely unnecessary atrocity." To be fair, many other Web CMS tools have their own scripting languages (e.g., Stellent's "iDoc") or use obscure tag libraries. Regardless of product, make sure to understand the long-term development implications of any package you select.