I love it overall. I plug my phone in and stick it in a cubby and close the door. No reason to take my phone out until I get to where I'm going. If I'm just doing a short trip sometimes I don't bother and just use bluetooth.

+Google Maps is the biggest one. So much better to not have to try and glance at my phone screen.
+Not using the cars stock shitty UI
+Siri
+Easy to listen to and respond to texts
+Bonus of your phone getting charged
+It's a lot easier to switch music than unlocking my phone and scrolling around

- You have to plug your phone in

Btw, you should still be able to use your steering wheel controls with bluetooth...