Don't get me wrong, I'm not saying it's perfect either. Nova is pretty weak as a villain, and the "debauchery" was a little too on the nose in the first 30 minutes. Some of the action scenes could have been framed a little better, too.
I just don't entirely agree that the plot is messy, but it is very simple. I expected an expletive-filled, violent, fun 2-hour film, and that's exactly what they delivered. There's a little bit of heart to it, but it's more on a surface level.
But at the end of the day, it's Deadpool - and that's the character. Everything is META. As I said before, the film was intended as a send-off to Fox's timeline; and the disintegrating plot/The VOID seems to be an allegory to Disney ditching it to make their new X-Men set in the 616 timeline.
Outside of Cavill, which it's possible he may be the new Wolvie in the MCU X-Men, each cameo served as a nice joke/purpose. So 1?