Well I’d say get over to the Garmin Forum sharpish, register too. Then scan the 810 threads.. all of them.
Do the 4.2 update.
Get OSM if it doesn’t have it.
Get Connect.
Get Express.
Get Strava.
Get a HRM.
Get a Cadence sensor.
Get a Ordinance Survey map of the areas you are interested in.
Once in Connect you can look up routes and then download them and/or create your own. Pretty simple to create routes, save them and share or download others and modify too.
As for the device, well it’s pretty intuitive, turn on and load your details into it. DCRainmaker has a lot of info on the device, best off going there for a peek. GCN did a bit on it too so thats helpful.
As for a lot of us, well we’ve sort of settled into the fact that it’s not the best at recording (all) rides on occasion due to freezes and such. But we’re all kinda happy with it. Most of the bugs on TBT have been fixed too..