I usually plug my Aluratek in once a week. Sometimes, though, I'll just plug it in while I'm using the computer, to top off the battery.
I've found its battery capacity to be good, sufficient for my needs. My Sony's battery life is longer, just due to the nature of e-ink vs. reflective LCD, but really, I'm not going to be in a jungle or a desert somewhere for any extended time where I would not have access to an electrical outlet. I think that those people who let the battery time be the deciding factor in their purchase are rather foolish; both types of screens allow you to read at least a full book without charging. Going multiple weeks without charging the device is nice, but really, I have to recharge my cell phone every few days - what's one more device?