Automation Testing is good for Regression Testing because after every sprint, testers have to test the whole application.
Automation testing although reduces the tester effort a much but still it has few hurdles and drawbacks.
Few of them are as follows:

1. Automated scripts are created in specific language and for creating scripts, testers should be skilled in programming language.
2. Automated scripts depends on the framework and framework is language dependent. So, the tester should be good in different programming languages.
3. Several testers use different techniques to write test scripts, so the readibility and maintainability of test scripts becomes difficult.
4. Generating reports from the test result requires very skilled testers.
5. Maintainance cost of automated scripts is very high when tool is updated with its new version.
6. Test Automation tools are very costly.
7. Automation Scripts failure probability is high when the requirement gets changed frequently.