Why do most people feel the first half is better?

A lot of people on here say it goes down in the last half for various reasons, but that's when I thought it started to pick up. The first half was full of cliches we've seen a hundred times before, mostly the police procedures and the jurisdiction stuff. There are so many movies where the clashing good guys argue over who's jurisdiction it is pointing out reasons, that cancel out other reasons... however in real life it is never up to the detectives to decide and the law has already decided.

They already know what is what so why come to another cop's crime scene and fight over it? It's not smart stuff for the audience and the first third definitely dwells on it. So what's there to like the first half really?