Pretty good info here. I was on hydrocodone for a little over a year and can say the withdrawal is difficult but not horrible if you don't have major chronic pain. For me the drugs managed the pain from a leg injury pretty well, and the occasional grinding of 10-20 pills, a cold water bath, and a couple coffee filters made for a few very nice weekends. I never really had any negative experiences on or off the drug.
One comment about hydrocodone preparations without the APAP: these preparations are schedule II substances, while the APAP blends are schedule III (hydrocodone blends with 15mg or more hydro, as well as all oxycodone preparations, are also schedule II). I'm sure everything's on the up-and-up here, but just in case it isn't, anyone planning to access the drugs should be advised that the law views pure hydrocodone and APAP blends differently.
A couple nitpicky points about some earlier comments. First, while the APAP in Vicodin is responsible for the lion's share of the liver damage these drugs can cause, orally administered hydrocodone is metabolised in the liver and can cause liver damage on its own, especially in the large doses some addicts need. Also, I have to disagree with the earlier comment on the relative opiate strength of hydromorphone. It's a tough addiction and a powerful substance, probably stronger than oxycodone, but it has nothing on fentanyl.