Mine is mounted to a dock in the instrument panel, so I can’t comment on handheld battery life.
I use it as an additional map display, and usually I leave it on Terrain / Weather (with traffic alerts) all the time. It seems good for terrain/obstacles and airspace, basically just like Garmin Pilot would be on a tablet. If/When my iPad overheats, I can still get airport info and approach/tower frequencies from the Aera. There is suppose to be a way to show restricted areas and airspace on the main map, but this doesn’t work for me when I have Terrain/Weather on also, so I have to switch over to the Sectional chart map to see them. (In reality I use my iPad or 430w to see nearby airspace).
The only thing I get on my tablet , that I can’t easily see on my Aera, is taxiway designations for complex airports. I can zoom-in on the Aera but it doesn’t show the letters/numbers of the taxiways like Foreflight does. The Aera is supposed to have “safe taxi” but either I don’t know how to use it, or maybe it is an extra subscription I don’t have.
Updated are done via WiFi, Need a subscription similar to Garmin Pilot or Navdata updates for any other Garmin navigator. If I had Garmin Pilot subscription it would make sense to combine all under a single update package price, would save some money on the NavData updates.
this info maybe incomplete because I don’t use the Aera as my “Main” EFB, it’s really just there in my panel as a screen for Terrain, Ads-b Weather and Traffic awareness fed from my GDL-50, and for that it works great.
one thing to add about terrain is that if you don’t have a flight plan / destination programmed in, and you start to land at some smaller place, the Aera sometimes doesn’t know that you are intending to meet the ground so it barks “terrain pull-up” warnings if it doesn’t see a destination airport nearby. My avionics shop added a serial-line so that the flight plan from my 430w is auto-filled to my Aera660 which is really nice.