I think that's a very fair assessment. The middle third of the film along with most of the Anakin-Padmé romantic interactions really weigh the film down because the story goes nowhere and the wooden acting between Hayden and Natalie elicits more embarrassed chuckles and eyerolls than it does sympathy for what the two characters are experiencing.
The movie starts of really well, then drags like a tired snail with almost no reward and finally delivers a slam-bang action sequence and finale worthy of the better films. But that middle....yikes. I don't mind Obi-Wan's investigation into the plot to kill Padmé but it takes forever and a day to end up in Dooku's clutches on Geonosis and by the time Obi-Wan evades Jango Fett and lands there you're checking your watch. The mystery starts off in a way that hooks you (mysterious, unseen cloners? Missing planet in the Jedi Archives? The hell?!) but then just plods along until you're basically glad that Dooku and the Separatists capture Obi-Wan and chain him to that column in the arena.
Anything to get the last part of the film going!