Camera mouselook / orbit

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

public class Player : MonoBehaviour
{

    float rotationSpeed = 5;
    float rotationX = 0F;
    float rotationY = 0F;

    void Update()
    {
        rotationX += Input.GetAxis("Mouse X") * rotationSpeed;
        rotationY += Input.GetAxis("Mouse Y") * rotationSpeed;
    rotationY = Mathf.Clamp(rotationY,-90,90);

        xQuaternion = Quaternion.AngleAxis(rotationX, Vector3.up);
        yQuaternion = Quaternion.AngleAxis(rotationY, Vector3.left);

        transform.localRotation = xQuaternion * yQuaternion;

    }
}