Seems like the reviews consistently mention the villains as the weak point.
Which can be good or bad. In a movie like Thor where the main characters are safely established, the lack of a compelling antagonist in the sequel was a big letdown.
In a movie like Guardians where Gunn has to split his focus between introducing so many cosmic elements to the MCU, introducing all these characters and villains, and bringing them together as a team worth rooting for, I don't mind if the villains take a backseat.
I just hope Ronan isn't the caricature he seems to be from the trailers and that they don't just kill him off and neuter future development. He deserves a lot more than that and Pace is a great casting choice for some of his more iconic moments, which I hope he gets to act out later in another installment.