Pros
If you work at a place that accepts tips, the pay is actually really good for a first job. The work itself can get old but usually you work with people you can at least get along with. It is all dependent on store though. The manager in most cases influences how the work environment is.
Cons
If you get stuck at a place with a bad manager, you will hate your job. Dunkin Donuts locations are so small that you are always interacting with the manager. If they are not nice, friendly, tolerable of mistakes, you may have trouble working there. Some stores have really high turnover solely because of the manager. Also, there is not much room to be promoted. The highest level is store manager, which can be a decent job, but the pay isn't too great and the hours can be long and stressful for such a low pay.