One of the few component (pull) web framework. It's philosophy you should learn, before you choose a web framework for a new project.
Ranked in these QuestionsQuestion Ranking
Pro Clean code, change of code philosophy
Clean structure helps you maintain your code for a long time.
Pro Saves you a lot of work
To save your work you need to understand its philosophy.
Con New releases unlikely
No major releases since 2008 when version 5.0 was released. Current version is 5.4.3 released in 2017.
Con Long way to learn it
It's philosophy is radically different to what you probably ever seen.