The functions of the 855 are great.I like being able to replace the battery when the original wears out eventually since it's much cheaper to replace than sending a unit to Garmin for battery replacement.The custom avoidance feature is a nice function not found in many other Garmin GPSs.  You can save avoidance instances to certain roads or areas you don't want to travel through.Ease of use is great similar to my 760 I had given to someone.The lane assist is nice.The junction view where it shows exit signs has very few exits in the unit, maybe they will add more in the future.Only main con I would say is an occaisional hang of the GPS and I have to hold the power button for a while and then it does a full reboot.Also the voice recognition does not respond sometimes, but it's still a great feature to have.Hopefully these will be ironed out in a future firmware upgrade. 

Question: What is the importance of that feature to you?
Answer: The custom avoidance feature is a nice function not found in many other Garmin GPSs