Decision to go with Manual testing or Automated testing depends on the current project situations:

1. Go for Manual Testing in the following cases:
   Unstable Software.
   To explore New Software.
   No Automation suite available.
   Adhoc testing (unplanned test cases).
   Not critical project & only one time testing & the effort required is less than the effort required for automation.
2. Go for Automation in the following cases:
   Stable Software.
   Any application with a High degree of risk associated with the failure is a good candidate for test automation. (Aircrafts, Patient monitor,)
   Testing needs to be repeated.
3. Advantages of Automation:
   Accelerate releases (reduces regression effort)
   With repeatable tests ensure consistency across multiple supported platforms
   Greater Application Coverage. Can test more often & more completely
   Convenient test reports for analysis