Its a fantastic app - I've been using it for about two weeks and its completely replaced a clunky process of trying to link lead spreadsheets, with Highrise contacts and Gmail emails. We store contacts in Highrise but it is pretty lousy for pipeline management. Because Streak lives inside gmail, it makes it really easy to see all the email associated with each lead. It also replaces Boomerang (email scheduler applet) and Tout (email template app) so I can get more done without leaving my inbox. Streak and Rapportive handle almost all my CRM needs at this point.