Originally Posted by Mike_73
May be so. But does this make them worse?
It guess it depends how long you intend to keep the device for. A typical lithium ion battery, used by virtually all current eBook readers, will have a usable lifetime of perhaps 5 years. After 3 years, it might have lost a third of its original capacity.
If, like me, you change reading devices about as frequently as you change your underwear, this is no issue at all - I've certainly never had ANY device on which the battery has died of old age. If, however, you intend to buy a device and keep it for 10 years, it may perhaps be an issue. It's something that each buyer has to decide for themselves.
Certainly, though, having non-replaceable batteries has never harmed Apple's sales.