Most patients do get pain relief. This can be full or partial. Patients with higher levels of pain before the surgery who get pain relief seem to feel the results are much better. This is compared to patients with mild to moderate levels of pain who only get partial pain relief.
Level of activity and motion are also used to measure results. A poor result means there's been no improvement or the patient is worse. X-rays showing neck motion (flexion and extension) may be helpful in showing progress. Fusion should limit motion at the level of the fusion. Any motion at the fusion site would signal less than optimal results.
Recovery can be slow at first. Most patients need at least eight weeks for the initial phase of healing. Your surgeon may have you wear a soft collar during this time period. Improving overall motion and strength comes later.