Battery life alone should cover at least $100 of the $399 iPad Mini vs. $229 Nexus 7 debate. I've been able to squeeze just 8 hours max out of my Nexus 7 and that was just doing light browsing and some Plants vs. Zombies 2. If I did that on an iPad it would probably last 16 hours.
Ive been using my iPad off and on all day since 5am.