Battery life is definitely excellent on the newer models. I can get at least a week of battery life on my 950 with Wi-fi on. I don't usually turn wireless off. But I could get about 2 weeks with wireless off on my 900 so I imagine the 950 is a little better.
Battery life and page turns weren't really factors when I decided to upgrade. I thought they were pretty good on the 505. It's the extra benefits like the touchscreen, better screen contrast and built-in dictionaries that made the sale for me compared to the 505.