Toio said:
Sweden is profoundly awful until at least assault and cannon appear. After allying with Muscovy, I had a 3 year siege of Ingermanland ultimately fail, despite sending in extra men every winter to make up for attrition. Muscovy ended up winning all the provinces, of course. Denmark and the Baltic states are even tougher than Muscovy for Sweden; even German minors can give it problems. Of all military failures, Sweden's are some of the most notoriously awful. I had more success with Brandenburg than Sweden.
Sweden still has the best potential of Scandinavia, due to Ugric culture. It's overall a very mediocre nation until much later, where it becomes slightly above average, by Latin standards at least. It's just barely big enough that it can somewhat control its own destiny, instead of being mostly at the mercy of random events and insane combat outcomes. I wouldn't recommend Sweden at all for beginners.