I felt the movie was very good until Dr. Manhattan left Earth. Then I think Snyder realized that he only had like an hour left because no one would stay for a 5hr movie. I expected some cutting and changes but it was very unbalanced as all the slashing happened near the end.
As a plain movie? Entertaining. As an adaptation? Disappointing.
Replacing the squid made a LOT more sense than I would have otherwise thought, they worked it in well with the whole quest for renewable energy.
The other parts of the changed ending sucked though. If they had time troubles they did not need 10 minutes of Ozymandias rocking Rorschach and Nite Owl II, nor did they need to glorify the thug robbery or the prison break fights that much. Changing Dr. Manhattan's departure from Earth and giving the "Nothing ever ends" line to Silk Spectre was pointless and totally ruined the line.
For other edits... The Rorschach bathroom scene was a pretty pointless change, and they cut out way too much of him vs. the psychiatrist. I thought having the thugs saw the guy's arms off instead of killing him was a bit of pointless gore
Acting... Dr. Manhattan, Nite Owl II, and Rorschach were all well done. Silk Spectre's actress was TERRIBLE. Ozymandias was off too, way too scrawny and came off too much like the typical comic book villain that he was explicitly made out not to be in the novel.
I probably had way too high expectations for it as an adaptation. Worth seeing if you haven't read the novel and need to be introduced to the material.