Camera-relative character movement controller. Does not handle animation, but has some comments where you'd want to add the hooks

CharController.cs

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

namespace PixelWizards.GameSystem.Controllers
{
    // the data model for the character controller. I like to keep vars like this in a separate class to organize them
    // and keep the main controller script as clean as possible. 
    // because it is set to be serializable, these vars are exposed in the editor (except where noted) when you attach
    // the CharController component to your character
    [System.Serializable]
    public class CharacterData
    {
        public float walkSpeed = 1.0f;
        public float runSpeed = 6f;
        public float slowDownModifier = 10f;
        public float moveThreshold = 0.1f;

        public float desiredSpeed = 0f;
        public float currentSpeed = 0f;
        public float jumpSpeed = 8.0f;
        public float gravity = 20.0f;

        public Vector3 moveDirection = Vector3.zero;
        [HideInInspector]
        public Vector3 lastDirection = Vector3.zero;
        public Camera mainCamera;
        [HideInInspector]
        public Vector3 forward;
        [HideInInspector]
        public Vector3 right;
        public float h;
        public float v;
        public float moveSpeed = 0f;
        public bool isMoving = false;
    }

    // the actual monobehaviour that you attach to your character. 
    public class CharController : MonoBehaviour
    {
        // set up the data model. 
        public CharacterData model = new CharacterData();
        private CharacterController controller;
       // public AnimController animController;  // hook up animation controls if desired
        
        private void Start()
        {
            // animController = GetComponent<AnimController>();
            controller = GetComponent<CharacterController>();
            // automagically find the main camera in the scene
            model.mainCamera = Camera.main;
        }

        private void ResetInput()
        {
            model.isMoving = false;
        }

        private void Update()
        {
            ResetInput();

            // save where we were going last frame so we can lerp 
            model.lastDirection = model.moveDirection;

            if (controller.isGrounded)
            {
                // camera-relative movement
                model.forward = model.mainCamera.transform.TransformDirection(Vector3.forward);
                model.forward.y = 0;
                model.forward = model.forward.normalized;
                model.right = new Vector3(model.forward.z, 0, -model.forward.x);

                // grab input
                model.h = Input.GetAxis("Horizontal");
                model.v = Input.GetAxis("Vertical");

                // figure out which direction we're going
                model.moveDirection = (model.h*model.right + model.v*model.forward).normalized;

                // apply move speed - add run / other move modes and apply their movement speed in a similar manner
                model.desiredSpeed = model.walkSpeed;
                model.moveDirection *= Mathf.Lerp(model.currentSpeed, model.desiredSpeed, Time.deltaTime);
            }

            // apply gravity
             var gravity = model.gravity*(Time.deltaTime*50); // multiply delta time by magic # to get gravity working properly. wee
            // apply gravity
            model.moveDirection.y -= gravity;

            // Actually do the move
            controller.Move(model.moveDirection * Time.deltaTime);

            // look the way we are moving (rotates to face direction)
            model.moveDirection.y = 0f;
            model.currentSpeed = model.moveDirection.magnitude;
            if (model.currentSpeed > model.moveThreshold)
            {
                // tell the animation system how fast we are going
                //animController.SetMoveSpeed( model.currentSpeed);
                transform.rotation = Quaternion.LookRotation(model.moveDirection);
            }
            else
            {
                // tell the animation system that we've stopped
                //animController.SetMoveSpeed(0f);
            }
        }
    }
}

A very basic camera-relative character controller that will rotate to face towards the direction the character is moving.

Every time I have to build one of these I can't find a good sample to start from, so here you go.

You can see the comments where you can communicate with a separate component (dubbed AnimController) to set variables for mecanim etc to control animation blends etc.

fixed the 'getcomponent' and variable creation in Update