I'd say I use my Forerunner 610 equally as a GPS when I run and as a HRM when I do workouts at home. Garmin Connect is limited in what I can do to categorize these workouts and it would be nice to allow for custom categories and activity types so that I could get better reports on how my progress is tracking. For example, I do a lot of P90X workouts, if I could categorize as "Resistance", "Plyo", "Cardio", etc., I could then track improvements based on these categories.
Garmin Connect syncs with my company's health incentive program - which is why I use it as HRM - to get credit for a workout. I'd assume others out there use their device as an HRM often as well - so it would be nice to see some features of the application support it better.