[eluser]Pert[/eluser]
Morning,
The benefits are you can do whatever you want or have to when building admin area. Lets say website you are building deals with events, but each event has some weird attribute that is required, but popular plug-ins for lets say Joomla do not offer.
So if your site requires something, it's relatively easy to build it, because all the code is yours so you know exactly what implications this new feature will have and if it might break something else.
The down side is, you have to do whatever you want yourself. It's not hard with CodeIgniter, but depending on the size of the project you might be spending some time to write your own admin functionality.
The way I see it, CodeIgniter gives you very basic stuff, and if you want to, you can build your own custom admin area that is easy to apply to any of your future projects. I prefer it like this, I'm not bound to use someone elses admin area and say to client - look, this is what we have, and that's that. I can implement my own UI to make it better for end user.