What makes a movie look amateurish is poor (or no) lighting
and (surprisingly) poor audio. In most cases the reason a movie
looks amateurish is because of the people involved and not so
much the camera. People who are not yet confident in their
skills and have little experience tend to make amateurish looking
movies regardless of the camera. That camera doesn't have a
mic input so you will need an audio recorder and a good mic to
get good audio. However, with excellent lighting and all the others
necessary things (good script, good actors, attention to art direction)
it is capable of getting an image that doesn't look amateurish.