I've never paid much attention to Peter's speech to Cornelius in Acts 10. When you've got four entire Gospels to study, there's not much need for a two hundred word summary of Jesus' life and mission.
This line, in particular, struck me as almost humorously understated:
He went about doing good and healing all those oppressed by the devil, for God was with him.
"He went about doing good" makes it sound like Jesus brought meals to shut-ins and spoke before zoning boards about improving pedestrian crosswalks. People who go about "doing good" may not always be exactly popular (recall C.S. Lewis's, "She's the sort of woman who lives for others -- you can always tell the others by their hunted expression."), but they're unlikely to wind up put to death by hanging on a tree.
I have to think, though, that this is more a mark of the ongoing debasement of the expression "doing good" than of the wishy-washiness of the original Greek. Peter saw the good that Jesus went about doing. He saw a dead child return to life, a leprous face become clean, and in seeing these things he came to believe that Jesus was the Messiah, the Son of God. That's not the sort of thing you talk of lightly.
(The same holds, at one remove, if we suppose Acts 10:38 is a Lucan paraphrase of Peter's actual words. Luke did, after all, write another book, too.)
But what about that "oppressed by the devil"? Well, if we manage not to smile at the backward superstition of the inspired authors, it's still hard to avoid the impression that people in First Century Judea were disproportionately oppressed by the devil. Nowadays, the devil might be thought to have a hard time getting a tempting word in edgewise between the world and the flesh.
At its most fundamental, though, what is the devil's oppression but a falsehood that leads to death? To be healed from oppression by the devil is to be freed from a death sentence. Freeing people from a death sentence is what Jesus went about doing, even those who didn't have seven or more demons in them. He was sent "to bring glad tidings to the lowly, to heal the brokenhearted, to proclaim liberty to the captives and release to the prisoners."
And if we think that, apart from Him Who is the Truth and the Life, we aren't captives and prisoners, then no wonder the devil doesn't work any harder at oppressing us. Even today, "all those who are oppressed by the devil" means all of us.