I tend to forget about imaging-resource.com but they have pretty thorough reviews, and a pretty nice still life set that they test all their cameras against. This makes comparing different cameras quite more straight-forward. Anyway, they have a write-up on the A850
http://www.imaging-resource.com/PRODS/AA850/AA850A.HTM
Here's a summary of the pros and cons.
Pros:
* Extraordinary resolution, nothing touches it at its price point, but there's literally no other full-frame DSLR at its price point anyway
* Built-in SteadyShot image stabilization
* Good color rendering: Natural without seeming flat (slightly more saturated than the A900)
* A lot of nice user interface touches, well thought out controls
* Intelligent Preview feature is a real time-saver for determining best camera settings
* +/- 2 EV steps on auto bracketing is nice for HDR (High Dynamic Range) shooters
* RAW files are truly RAW! (Able to turn off high-ISO noise reduction in the RAW files)
* Huge viewfinder image, really hearkens back to the days of film SLRs (in a good way)
* User interchangeable focusing screens
* Lighter than many other full-frame SLRs in its resolution class
* Rugged magnesium alloy body
* 3.0-inch, high-resolution LCD
* Top panel LCD (albeit a small one)
* Dramatically low price for a full-frame camera with this much resolution
* HDMI output
* Good battery life
* Dual memory card formats
Cons:
* Some image noise even at ISO 200

eek

* At anything above ISO 200, noise limits maximum print size before resolution becomes an issue
* High-ISO performance doesn't match that of competing full-frame models (but all such are a good bit more expensive)
* Dynamic range of JPEGs less than that of many current models, though excellent dynamic range expected from RAW files
* Viewfinder resolution dropped to 98% vs 100% for the A900
* Top frame rate only 3fps; lowest among full-frame DSLRs
* Slower frame rate translates into noticeable early shutter penalty (it won't fire if you press the shutter button too soon after previous shot, A900's "dead time" was much less apparent)
* Noticeable delay when switching from record to playback mode is annoying
* Despite being much lighter than its's only competitor, still a big, heavy hunk of metal and glass (not the camera's fault, just a fact of life with full-frame.)
* No built-in flash (not unusual for a pro model though)
* APS-C mode does not improve burst speed
* Exposure accuracy may suffer with DT lenses in APS-C mode
* No Live View mode
* No Movie mode