Now, I myself have built my own MVC framework and have recoded various parts of my site to work with it. I must say, though there's extra work involved with maintaining more files, it does make things easier to fix in the long run, and also opens up new possibilities when one considers that the views and models can be adapted. Say you have a forums topic view which normally outputs a standard topic page such as you are reading right now. If you want to later add a printer-view mode, then that's as simple as adding a new view: the controller and model stay the same.
Or say if your data source changes from a database to an XML file. Without MVC, you'd have to rewrite a bunch of files to remove the SQL queries and change the logic. With an MVC model, then just the model changes, since the rest of the app's logic doesn't have to deal with how the data is getting to it, just that the data does get to it.
There's more advantages than just these, of course, but I'll save those for later.
