It is not a huge city, but there are many historical places to see around. It is a calm city, and easy to access to the Trinidad ruins.
I went to Encarnation for carnaval, because it starts earlier than Brazil. The carnaval was great, but without it the city is not yet ready for tourism.
They try hard giving you maps and encouraging you to visit Jesuit mission ruins, and even built a beach on the river, but still the beach needs some trees and shades from the sun, and there needs to be a tourist bus to take you to adventures. Currently little adventures in the area.