To what extent were Isabella and Ferdinand good rulers of Spain?

Someone who makes a good ruler has to make right choices for the people and the country (or state), should be able to protect their people from invaders and should be capable of keeping if not increasing the country's wealth. This means making sure that the military forces are well organized and powerful, staying friendly with all the neighboring cities (but that is not a must as long as the armies are strong and competent), states and countries as well as keeping up with all the money coming in to the country from business, trade, foreign affairs and colonization (which gives access to cheap labor, favorable tax scheme, less expensive resources...). And although that may not sound too complicated one other necessary action is making sure that your people are not against you. They do not all have to support you, but if many or all the people are against their rulers that can result in a rebellion or they might even the ruler if that is what it takes to get rid of him or change to his mind.

English: symbols and CoA of Ferdinand of Aragon an...

English: Ferdinand II of Aragon and Isabella of Ca...

Isabellas

The people living in Spain in the 15th century varied a lot in cultural backgrounds, ways of living and mainly in religious beliefs. This was because the Arabs invaded almost all of Spain by the 7th century, and since they had brought with them the Muslim religion, a large part of Spain was Muslim, but even though most of them worked for Spaniards as craftsmen or business men, among them were also the rare wealthy Muslim families who owned lots of land and slaves. There were also quite a large number of Jews among the Catholics and Muslims in Spain, so for the very beginning of Isabella and Ferdinand's reign you could say that Aragon and Castile were multi-religious, but...