I've had mine since December and there is no sign of battery issues. It still runs strong all day for emails, a few game sessions, YouTube views, and various other activities. And sometimes a day and a half, before a recharge is needed.
I think it all depends on how much hard use it gets (meaning processor intensive stuff). But, the battery does last quite a long time.
Remember that batteries do age, and over a couple years there will be a noticeable decrease in performance, but it should be very gradual. By then I expect I'll be ready for a replacement anyway. So, I'm not really concerned.