I'm surprised to see this discussion still going. The new iPad 4 also introduced a new 12 watt charger that noticeably alleviates the slow charging people were used to with the iPad 3. I figured that information would have been widespread in this forum and discussion by now.
As someone who also owns an iPad 1 I know how quick it and the iPad 2 can charge. I had also bought and returned the iPad 3 precisely because of the slow charging. So when the new iPad 4 came out and I saw that the charger was updated I thought I would give it a try. How does it compare?
Well, if you are someone like me that is very picky about battery life and charging times, the slow charging issue is now not really much of an issue anymore with the iPad 4. Does it charge as quick as an iPad 1 or 2? Of course not, but it is certainly better than the iPad 3 with the old 10 watt charger. For one thing, I believe there were things done under the hood of iOS and the hardware on the iPad 4 to help things out more than one would think an extra 2 watts of power would provide. A second thing is the battery life on my iPad 4 is noticeably better than the iPad 1. Couple those things together and I am now reasonably satisfied with the charging times and especially the battery life of the iPad 4 in comparison to my iPad 1.
People also need to keep in perspective the fact that the benefits of iPad 3 and 4 demand a lot from the battery in comparison to the iPad 1 and 2. My advice to everyone with an iPad 3 is to get rid of their current charger and buy the new 12 watt version. I believe the 10 watt model is not even sold anymore but I would double check to make sure you are buying the 12 watt version. If there were software changes made to iOS 6 to help the iPad 3 with charging and battery life then so much the better.
After you do that, check to make sure your charging time has improved and if it has then forget about the issue and enjoy your iPad. If you feel your iPad is faulty then call Apple.