Alberto, a PM on the Activities team who drove our BPEL release, mentioned that there have been over 3000 downloads since March when we first released our BPEL CTP. However, we havent heard feedback from customers, making us think that most customers may not be aware of our Connect site: http://connect.microsoft.com/wf. Paul posted on his blog as well.
Infact, not just for BPEL, I would like to request you to reach us with your comments and feedback on other pieces of WF as well via the above site. We track these bugs regularly and its a great way to get communication started with the team.