I thought the same thing on the 4S! They put a better CPU and camera into the exact same phone. I figured there would be a rebellion among customers. Instead, they bought 37 million of the things in the 4th qtr of CY 11! Apple could put sand in ziplock bags and sell them by the millions. The one thing I was looking for was better wifi performance. Ipad 2 stinks compared to a laptop. The laptop works in your hotel room and the Ipad 2 can't even see the networks.
I think the iPhone was a little different story. There are a number of people around the world who have bought into the entire iPhone franchise. After a couple of years their phones go obsolete and they either have to leave their ecosystem for a new platform, or stick with iOS and get the latest and greatest that Apple offers.
The impressive sales figure say less about the market agreement of the validity of the 4s as much as it says that people are happy in their ecosystem and are ready for another iPhone and another 2 year contract.
The iPad is a different story. There are no subsidized rates, and no contracts with the exception of the wireless service on certain models. To look at the sales figures of the 4s and suggest a similar sales cycle is kinda foolish. We'll see in six months where the new iPad rates.
I noticed that too. Intel has certainly optimized the experience of wifi over the years. I also have a first generation iPhone. So many wifi signals it misses that even my netbook picks up easily. And those that it does pick up, it has a difficulty connecting to. In other words, my cheap $250 netbook kicks iPhone's butt in web browsing in wifi locations. Apple's Mac line is very similar to PC experience. It would be foolish for Apple to say that their iPads and iPhones are good enough to forgo the replacement of an aging Mac. The current growth of iPhones has more to do with stealing market share from other smartphone makers such as Nokia. The current growth of iPads has more to do with the fact that it's a new form factor and a cheap way for someone to have Apple OS and App useage capabilities. Less likely for iPads to be replaced like the iPhones are, since iPhones go along with a phone plan which subsidizes the cost of the smartphone. It's not cheap to get a plan with an iPad, so iPads are used more for wifi locations. By the time someone thinks about replacing their iPad with a new version for at least $500, they will have choices of hybrid models putting a laptop and tablet into one.
The iPad is an interesting general purpose human interface appliance... and actually MAY be all that is required by the AAPL target audience ("computers for the rest of us", Translation: dummied-downed devices to cater to the LCD of society... who probably were never qualified to own a real computer in the first place). They are certainly NOT a PC replacement for those who create. They may however, indeed grow to fill a significant 'void'.