Strange topic, I know, especially since many of us are probably huge Deadpool fans, but come on! There has to be something you hate about Deadpool!
For me it's something very specific and it has to do with the "new" Deadpool, who has been around for a while though. After Way took over to be exact:
I really, really dislike the fact that Deadpool does not have a dark side anymore. Do you remember the rare moments in old Deadpool comics, where he was kind darky-funny or something, but then there was a moment where he simply snapped and you knew that some serious shit is going to happen very fast? I absolutely loved that and was always looking forward to these moments, which would show a different side of Deadpool.
That's simply not around anymore. Unfortunately. I also miss Bob and Blind Al. I missed them for quite some time now, but now with the recent on-going and the new "sidekicks" he has, I realize how interesting his relationship with the other characters was.