Someone who is amazed is surprised and overjoyed. If you are diving for sunken treasure you will be amazed to discover a wreck filled with gold bars, unless the gold in those bars turn out to be paint, in which case your amazement will quickly turn to disappointment.
Amazed means being astounded or filled with wonder. It's the kind of reaction you'd expect from an audience at a magic show, although it takes a lot more sophisticated magic to amaze audiences today than it did decades ago. Back in the 1930s, if a magician had pulled a rabbit out of a hat you would definitely have been amazed. Today, you would have to see a magician make a rabbit levitate, disappear, and reappear in the form of a tiger to get an amazed reaction.