What’s the best way to measure product usage?

Fred Wilson (Co-Founder and Partner at Union Square Ventures)
Social Commerce Is Commerce With A Social Layer – AVC

Conversion rates are critical. They tell you what systems perform best for the end user. When a system converts north of 5% of users visits to a transaction, it is working extremely well for the end user. When a system converts 0.1% of user visits to a transaction, it doesn’t work as well for the end user.