I got my AV8OR for free... Won it in a BK drawing at Oshkosh the year they were introduced. My opinion:
Pro -
It's a perfect fit between the grips of my yoke. Grumman's have a pretty small yoke. A 796 is really chunky and in the way... an Ipad pretty much blocks the entire panel. The AV8OR is just right... I can hit pretty much all the functions I need on it using just my thumbs without taking my hand off the yoke.
For instance, It can display 4 data blocks at a time on the left side of the screen. You can scroll between them with a quick thumbswipe.
Flightplanning is beyond quick and easy. Before, I had a Garmin 296 handheld, and it took FOREVER to put in a FP, so I pretty much used it in "serial direct-to" mode. The AV8OR has a nice QWERTY keyboard, including victor airways using arbitrary entry/exit points... or you can enter the FP graphically using the touchscreen map.
The built in antenna works great. It comes with an external antenna as well, but I've never needed to use it. Less wires and extra bits is always better.
The terrain database is very detailed... I do a lot of mountain flying, and the terrain functions in the AV8OR are far superior to my 430W.
XM weather works fine, and is bluetooth to the receiver, so no extra wires.
Outputs the flight logs as Google Earth KML files on an SD card.
BK has supported this fairly well, adding numerous new features to the software over the years (safetaxi, weight and balance calculators, XM radio tuner)
Cons-
This was obviously never designed from the ground up as an aviation product. It's some off the shelf receiver designed by an anonymous Chinese company, that BK just pad some anonymous dudes in India to write aviation software for. It feels and looks chintzy and kludged.
The touchscreen is no iphone, that's for sure. A bit hard to see in the sun, and not as responsive as we've come to expect from modern electronics.
The yoke mount that it comes with is clunky and hard to adjust. I bolted the cradle it comes with to a standard RAM ball and use the RAM yoke mount instead, much nicer.
It's common for the DC cigarette lighter power supply to die. I replaced mine with one from the aviation aisle of Radio Shack. As noted, it has an internal battery, but it's only good for an hour or so. However, it you want to carry a spare battery, it's actually from a Nokia cell phone. Did I mention that this was obviously never designed from the ground up as an aviation product?
Summary - I would not have paid 600 for it. The Garmin Aera 500 is a superior product in that price range. However for $150 it is a steal. Although BK will most likely not be providing future updates to the OS, I expect that map updates will continue for some time, as they are sold by a separate vendor.
BK as a company, is spiralling the toilet. Their booth at OSH was laughable this year. The sum total of their strategy this year is an Ipad app to compete with Foreflight... and Wingx... and Garmin Pilot... and Skycharts... Best of luck starting 2 years late in an supersaturated market with a nearly undisputed leader guys...