It is definitely a Deadpool movie. It's excessively/comedically violent, massively irreverent, and morally ambiguous--yet it still has a clear heart that makes me love the character. I would say any fan of the Deadpool or Wolverine movies will enjoy this film.
It also is filled with references and cameos that made me extremely happy as a Marvel geek. That said, I feel that the movie does a good enough of a job setting up the audience with at least most of the information that they would need before watching the film. In my mind, there were several missed opportunities and cameos that did not appear, but those were more than balanced out by unexpected elements and cameos that made the movie great.
There is also a post-credit scene that I felt was worth the wait.
I look forward to seeing it again--hopefully soon.