Where did this "3 years" come from on Li-ion batteries?
Keep in mind that nearly every hybrid and electric car on the market uses Li-ion batteries and have an expected battery operational life of over 7 years, not three. As such, the argument about the Li-ion on the iPad as a weakness is hardly valid. I'm still using a first-gen iPad and still get more than 5 days of standby time with no usage and it really depends on how I use it as to how fast it depletes its charge. Since I don't use it at home as much as I do on the road, three days of intermittent use is normal for me and almost two days of fairly heavy use when relying on a weak 3G signal where no other internet source is available. It still recharges to full power in about 3-4 hours of charging off the car battery port.
When will I buy a new iPad? When this one dies, or iOS itself advances to where its integration with OS X makes it that much closer to fully replacing a laptop so that I can do anything on it that I do on my desktop at home--including playing the same games.