I had a WP7 Lumia phone and had a similar experience. It was light years ahead of what Apple and (particularly) Android had at the time.

But it wasn’t Snapchat that killed them. Less than a year after getting my WP7 device I was told it was end of the line and never getting and upgrade to 8. The maps app was straight up bad. When faced with the decision of paying again for a WP8 device or switching, I switched.