What most people didn't like is what he did with the Mandarin and Black pulled his standard trick on the character. IMO it'd have worked better if even that was like a double role and him staying the mandarin for later. The rest of the film is quite OK. I mostly like Black's writing and directing, just seeing the same tricks over and over in terms of quipy dialogue and playing with expectations since Kiss, Kiss.
Monster Squad, only seen it once, but it reduced great monsters to poor characters.
The thing that ticks me off is the DNA splicing which is not needed at all if you ask me and clearly a lot of other fans. I could accept it if it is limited to a certain tribe, and now I'm kind of tempted to actually read the script. But I sort want to have some surprise when I enter the cinema...
I will go, it will be entertaining, it just reduces the Predators we knew to more generic monsters instead of keeping them a little more mysterious. I have little hope this will actually improve the franchise.