I have been using a Garmin Vivoactive for ages for both cycling and hiking. There are some very useful apps out there. I use it primarily to record my activities. Almost as important to me are the statistics and information it gives me:
hiking: sunset time, current elevation, mileage, pace
cycling: total distance, elevation gain (tells me how much climbing I have left), average speed (this really helps to plan especially on rides with lots of climbing)
I have it set up to auto-upload workouts to Strava and RWGPS. Don't think I'd ever want to use it for navigation, I really like OSMand, voice prompts, and seeing how close I am to an intersection when going downhill (can I let loose or do I need to be careful around the bend?), although even that app on a large screen isn't without flaws.