I'm unconvinced that battery life is important for something you use all the time.
Obviously it needs to last a day, but if you're frequently using it, charging it overnight isn't hard to remember.
If you don't often use it, battery life is critical because it's unlikely you'll remember to charge it... but if you're not using your PDA regularly, it's probably not a very good PDA (for your needs, anyway).
I think we all think we want long battery life. I just don't think in practice it matters.
There's an interesting difference (for me) between the recharge requirements for my phone, iPad, and Kindle. I charge my phone most nights (it'll last into the second evening pretty reliably on a charge), my iPad once a week or so, and my Kindle fairly rarely. I do quite appreciate the long battery like of the Kindle (it's an old 4th gen eInk display model, which doesn't go a whole month any more with heavy use, but even used a lot it still gets well over 2-3 weeks out of a charge).
I sometimes consider investigating rooting/hacking a Kindle to make it closer to a PDA - I suspect it's got a lot more computing power than a Newton did...
The weeks or months of battery life that my e-reader has is a game changer. It entirely changes how I think about maintenance of the device (ie. I don't).
True, but if it doesn't have power when you need it, what's the real impact? (Setting aside the inconvenience of, say, going on a flight and not having something to read.)
If your PDA doesn't have power when you need a critical piece of information, that's a real problem.
Obviously it needs to last a day, but if you're frequently using it, charging it overnight isn't hard to remember.
If you don't often use it, battery life is critical because it's unlikely you'll remember to charge it... but if you're not using your PDA regularly, it's probably not a very good PDA (for your needs, anyway).
I think we all think we want long battery life. I just don't think in practice it matters.