What do you mean, "mask" the pain? What do you think the Vicodin is doing? Any pain medication is going to mask the pain. Neither it or Gabapentin is an anti-inflammatory. Are you taking any anti-inflammatories? Also, I saw a commercial for Lyrica and the side-effects didn't seem any better than any other medication.
I don't know if Gabapentin specifically relieve the numbness or just made it where I didn't notice it. It really helped with the nerve pain, though.
The main side-effects that are really scary are related to people who take it for seizures. If they suddenly stop the medication, yes they can have a seizure. Also, if you are taking it for pain, weaning yourself off (or having a doctor help you) will help keep the pain from coming back. Yes, if you stop all at once (especially if you are taking more than 2 pills a day), the pain will come back.
If you are worried about the side-effects, talk to your doctor about it. Like the package says, the doctor prescribed the pills because he feels that they are safe and that the benefits outweigh the risks. Also, you can start out at a low dose and if you experience side-effects, you can stop.