If you're evaluating PrimeFaces for your project this section can help you. Design of PrimeFaces is based on well defined goals and principles.
A Different Point of View
Prime Technology is not a software vendor but a software development house along with the consulting&training activities. A framework that's not even used by its own creators can easily miss vital points regarding usability and simplicity, a major difference compared to vendor products is that we use PrimeFaces in all of our clients' projects as the front end framework. This helps us to view the project from an application developer's point of view so that we can easily realize the missing features and quickly fix the bugs. This significantly differs PrimeFaces from other libraries.
Simplicity and Performance
PrimeFaces is a lightweight library, all decisions made are based on keeping PrimeFaces as lightweight as possible. Usually adding a third-party solution could bring a overhead however this is not the case with PrimeFaces. It is just one single jar with no dependencies and nothing to configure.
Ease of Use
Components in PrimeFaces are developed with a design principle which states that "A good UI component should hide complexity but keep the flexibility" while doing so.
Strong Community Feedback
PrimeFaces community continuously helps the development of PrimeFaces by providing feedback, new ideas, bug reports and patches.
If you are using Spring Framework and looking for a JSF front-end framework, then your search is over as SpringSource suggests PrimeFaces to be used in JSF-Spring applications. Also Spring ROO only supports PrimeFaces in JSF addon. Please note that PrimeFaces is a UI framework and not coupled with a middleware framework like Spring, EJBs or similar.
Number One at DevRates
According to DevRates.com, PrimeFaces has taken the lead with overall rating 9.4 (at time of writing) as the developers’ favorite framework to create rich user interfaces with java.
Competitors Use PrimeFaces
Thousands of applications have been created with PrimeFaces, even competing products like IceFaces is powered by PrimeFaces. Following is a graph generated by Google Trends comparing the popularity PrimeFaces with the competitors. For many, PrimeFaces is the de-facto standard of JSF Component Libraries.