The battery life on N4 has been stellar so far. Under nearly identical load, on average it uses 5-10% than GNex and it's even better in deep sleep. Took it off the charger after it was fully charged and forgot to plug it back in. It used 1% while idling overnight.
I would probably feel the same way if I had any experience with the smaller tablets but I don't, I just jumped into the tablet market. I've been using an ipad 2 since I placed my order and I can definitely appreciate the difference in weight and thickness.
TWSS jokes aside, 7" is large enough for a tablet IMO If I need bigger, I wouldn't necessarily reach for a 10", rather switch to computer monitor or TV. I would buy a tablet with Exynos 5 pushing 1080p 7-8" over the Nexus 10 any day but I just couldn't wait anymore.