Genius
I once read a comment on these forums from someone claiming to be a (former?) Apple Genius.
If I remember correctly, he said that AppleCare was important for their computers, but unnecessary for their iOS devices, iPods, etc.
Unless, you are extremely hard on your iOS device, it (theoretically) should function well or as intended for at least the first two years of the device, without the need for AppleCare. If it dies during the first year, they should repair or replace it. If it lasts longer than two years, which seems likely, the AppleCare would have expired.
From my experience so far, my iPod touch has lasted just over two years, the battery capacity is a bit reduced and lasts a little less time due to normal usage and increased system demands of the more recent iOS upgrades. At that point you will decide if you want to keep using the same old product you have, or buy a newer version of the iOS device that you want for the newer/"snappier" experience of the upgraded hardware and features that may not be supported with the hardware of your older device.
The only risk to purchasing or not purchasing AppleCare for your iOS device is whether or not You think the device could break between the first and second year of use, and how much peace of mind you think you need not to worry about it.
If you treat your device with care, and have a good case for it, you might not need AppleCare for it. If you have the extra $100 to spend on it, so you don't have to worry about it anymore, then go ahead and buy it. I think it's more of a personal decision or preference than a device driven need.
Computers are more expensive and are more likely to need applecare to buy that piece of mind.
