I'm planning to develop a web application which will have many static pages (about, help, contact, etc.) and other dynamic pages for the application.
Most of the time I use CakePHP to develop any of my applications, but for this project I have being thinking about using WordPress as a framework for my applications. The reason is because in WordPress it will be easy to create the static pages (easy to write the static pages contents) and because the user registration in WordPress already exists (I don't have to build it).
But on other hand, CakePHP is easy for me, and I will be focusing in building my application, not learning a new framework.
Let me know what you think. Should I use WordPress as the core of my application or use CakePHP?
PS: my application will be mainly a search engine using Sphinx to look up large data in a database and display the result for the users and some other easy PHP (dynamic) pages.
One option to consider is setting up WordPress to serve your static pages (to avoid spending time reimplementing a CMS for this content) and using CakePHP to develop the dynamic application that is the core of what you're building.
You can then host them under the same domain, and if you set up the same page structure / CSS for both WordPress and CakePHP then it should be seamless to users.
A similar example I have is a site running WordPress for content management, and phpBB for a forum, both styled to look the same:
This does mean you have to maintain two page themes (CSS & HTML) and keep them in line with each other, but it does give the advantage of playing to WordPress's strengths of managing static content (about pages) and also time-based content (news articles) with a low time / effort investment, allowing you more time to concentrate on playing to CakePHP's strengths for your dynamic application that is the core of what you're building.
If you mostly use WordPress as it comes without doing much customisation / development, you should be able to get it running pretty quickly with a low learning curve, allowing you time to concentrate on your core application.