Pros: A county with an isolationist view would be able to remain out of foreign conflicts, international disputes, and remain entirely sovereign. A perfect example is Switzerland.
Cons: A nation with an isolationist view can miss out on economy boosting trade deals and agreements. Other nations bordering them may look at their neighbor as unreliable if a major power were to attack them, and may not garner any support for internal or external issues. An example of a county like this is pre ww2 Finland.