I did do something different in my version – I added an “ice” physics material to the player… To keep the player from “sticking” to walls you could add a Physics Material to the player’s collision that has Static and Dynamic Friction set to zero.  This will make the player slip right down the walls.  But it’s not good if your level has slopes since he’ll slide on those too.

Another way is to cast a ray out to the forward direction and if it the ray intersects a wall layer then stop moving in that direction. Check out the Player.cs script in my other 2D tutorial series for an example of how to do that.  http://www.rocket5studios.com/tutorials/make-a-2d-game-with-unity3d-using-only-free-tools-part-3/ (under the Hooking Up The Scripts section)

The past weekend was spent dealing with the woes of character controllers VS rigidbodies for player movement. I eventually settled on rigidbodies and my own control scripts though I am experiencing odd collision issues (similar to the phenomenon described above). I would be ecstatic if you could do a tutorial on using rigidbodies for players, or point me in the right direction. I’ve searched a ton and the script you provide here is the most complete one I’ve ever seen… 

Thanks for the tutorials Tim! They really helped