First Impressions

• Can't do one overall Criteria - eg IF this is a particular type of Campaign, then all the other criteria relate to this. 
  • You have to add that Criteria to each node of the process. 
• It takes the whole screen up - you can't quickly get back to other areas of setup. Open it in a new tab. 

Good Things

• Create a Chatter Post
• Create a Record
• Automate Publisher Actions
• Automate Flows

Things to Know

Reuse

• You can't re-use field updates, email alerts etc - this may be things that will stop you using Process Builder. https://success.salesforce.com/ideaView?id=08730000000DfNzAAK, https://success.salesforce.com/ideaView?id=08730000000DgFcAAK

Object

• You can't change the object that the Process runs from after you create the process. 

Emails

• You can use only email alerts that are associated with the same object that the process is associated with. The record that started the process is used as the starting point for any merge fields that are used in the email alert

Issues

Lots of known issues https://success.salesforce.com/issues_index?tag=Process%20Builder

Fields

• Can't use formulas for creating field values. Options:
  • Create the formulas in other fields
  • Use Publisher Actions
  • Use Flow Triggers. 

Using the fields selector has a few issues

• Can't search on the fields

Emails

• Email search only searches on the API name of the email. 
• There are NO options for the emails - EG who to send the email FROM. 
• Can't send emails from org wide addresses - now you would probably want to do this for about 99% of your emails https://success.salesforce.com/issues_view?id=a1p30000000T5cTAAS. 

Chatter

• Can't post to chatter on the related record IF Feed Tracking is not enabled on this record. 
• Can't post to the feed of a related record. See https://success.salesforce.com/ideaView?id=08730000000DftMAAS
• Can't @ mention a user (eg Owner). See https://success.salesforce.com/ideaView?id=08730000000DfbNAAS

Formulas

• OMG, can't use some major formulas in Process Builder. 

  "If a formula in a process uses any of the following functions, the formula will return null.
  • IMAGE
  • INCLUDES
  • ISNEW
  • ISPICKVAL"

• Formulas can only be 3000 characters, which is way less than even regular formulas, and usually the trick is to use Workflows to deal with larger formulas - back to workflows for this one. 

Auditing

• You can't see the actions that a process creates. https://success.salesforce.com/ideaView?id=08730000000Df9JAAS