I've been playing with the Gen 1 7" Galaxy Tab the past couple weeks and it's a mixed bag, mostly because of battery life. On the upside, for reading in bed, it's the perfect size and the weight is acceptable. It's also damn fast for an Android device - something most reviews don't bother to mention. I even got it to support voice calls via SIP and Android 2.3.
From a full charge however, it shows a whopping 90 minutes of runtime. I've found that for night reading, when the backlight is typically at its lowest setting, it does way better than this but it's nothing like my iPad which I may need to charge once or twice a week. You basically have to treat it like a cell phone - always mindful of where the charger's at - and that's a real game-changer over normal e-readers (or the iPad, to be honest).