In Christian ministry, the word "rebel" has an aura that is almost entirely negative. Rebellion against authority and especially against God's authority as it is displayed in familial relationships, civil government and biblical revelation... that kind of rebellion is the worst of vices, right? "For rebellion is as the sin of witchcraft..." (I Samuel 15:23). However, just like faith, hatred, jealousy, nakedness, eating, prayer, and many other moral, spiritual or practical issues, the context and the object are vital in evaluating the wholesomeness or depravity of the thing. I'm saying that Hezekiah's rebellion against Assyria was a good thing. It was a product of his true faith in God.
One of Hezekiah's descendants, Zedekiah, later tried rebelling against another invading gentile force, but that didn't turn out too well for him (II Kings 24:20 & 25:5 - 7). So, civil disobedience, a coup or even national defense should only be undertaken under the guidance of the Holy Spirit of God... we don't ever want to find ourselves in opposition to Him... on any level (Acts 5:39).
Anyway, Hezekiah was one of the best monarchs in history. In his 29 years as king, he obtained such a wonderful grade from God that we read in II Kings 18:5 that He followed God better than anyone had prior to his coronation and more perfectly than anyone who succeeded him after his departure. That's high praise indeed!
He wasn't perfect, of course. At the very end of his life he ended up paying bribery money in the form of tribute to keep the Assyrians at bay.