Pros: flexibility, automation and the ability to tie the script to other Google ressources such as Spreadsheets
Cons: You can only run the script on one account at a time. If you manage hundreds of accounts via MCC like I do, this is a drawback.
-It's made in Javascript, so the scripts will have to be maintained by people who are at ease with programming.
As a self-taught coder with limited experience, I was able to program most of my scripts very quickly. Experienced developer will find it easy. Just like any software, the big part isn't the coding, it's the training, testing, debugging, maintenance, documentation that take the most time!