After the Polaris update, when qualifying leads, the dialog box is no longer available to select the creation of Account, Contact or Opportunity. When the qualify button is pressed, CRM Dynamics assumes that the user wishes to create an Account, Contact and Opportunity. When we covert leads, our standard practice is to covert leads only to Account / Contacts. This automatic assumption now will create opportunities within our system that will have to be deleted as the recently qualified leads might not be ready for an active opportunity within CRM yet but our sales team wants their contact info available in Email and on their Phones.
In addition, we use Campaign Reponses to create opportunities from Leads/Contacts. We usually will covert the lead first then convert the Campaign Response to an Opportunity under that Contact. This allows us to tie our marketing campaigns to the opportunity which can't happen now as the lead conversion is automatically creating an opportunity.