I give Divergent a cautious thumbs up. Cautious because it was good but not that good.
To set the stage, I loved Divergent the book. In fact, I liked it more than The Hunger Games. I didn't like Insurgent or Allegiant nearly as much, but Divergent was close to perfect as young adult dystopians go. So I went into the movie with high expectations. And mostly, the movie lived up to it.
How closely did the movie follow the book? It's been awhile since I read Divergent, so my memory of the book's specific details is a bit fuzzy. As far as I could tell, it followed the book quite closely but not so closely that it forgot the cinematic value of the story.
I'd heard elsewhere that there was a lot more contact between Tris and Jeanine than there was in the books. I don't remember what contact they had in the books, but I thought that the interactions in the movie were fantastic. The chemistry between them was palpable. Jeanine was arrogant, confident, and cruel. Tris was puzzled yet defiant. I couldn't take my eyes off them.
On another note, I loved the set for Dauntless's compound, the Pit. It was exactly how I pictured it in the movie. Dark and cavernous with raucous chaos inside, both good and bad.
How was the acting? It was fine. I don't expect anyone to get an Oscar out of their performance, but I wouldn't say anyone did a bad job. I probably liked Kate Winslet the best. Not sure if that's because she's such a good actor or because her character was well written. Either way, Jeanine was compelling and believable.
Shailene did a good job. She effectively portrayed a character who was small and timid who excelled not through brute strength but through hard work and determination. A lot of that is due to the script, but Shailene made me believe it through her body language. Shailene did a wonderful job on the few scenes where she had to be really emotional.
Theo also did good work, but Four did feel a bit flat to me. This seemed more the fault of the script than Theo's acting. Four didn't have a big range of emotions.
1. It was tooooooo loooooooong. Divergent was almost two and a half hours. With rare exceptions, no movie should be two and a half hours. The movie flowed well and there was tons of action. Despite this, I found myself checking my watch multiple times during the last 30 minutes - the height of tension in the entire movie - and thinking "Is this thing ever going to end?" My husband (who also loved the book) didn't mind the length as much. He said that he didn't think they could have cut anything. I also can't think of particular scenes that they could have cut, but I still believe the movie would have been better if it had only been two hours.
2. Romance. Don't worry, there's plenty of Four/Tris romance in here. You see the characters go from initial distrust and dislike to respect and then ultimately to kissy kissy lovey lovey. But at the point of the movie where Tris tells Four "I love you," my instinctual reaction was "You do? Why?" They'd had a few make-out sessions and some emotional connection, but I didn't think the movie effectively showed that their relationship had progressed to the Love stage. The book captured the gradual build up better.
3. Will, Peter, Al, and Christina. I had the hardest time telling Peter, Will, and Al apart. They all were pale with dark hair and similar builds. Someone should have thought of that when they were casting. Eventually, I was able to distinguish their characters, but that was because I knew who they were from the book. Peter stood out after about 45 minutes, because he had more lines. Will and Al only had a few lines and were virtually interchangeable. If you hadn't read the books, you'd have no idea who they were or why you should care about them.
I liked Christina and thought she had just enough screen time to effectively cement her best friend status. However, they hardly touched on her romance with Will. I only noticed the subtle hints because I'd read the book. Admittedly this would have slowed down the plot, but it's important to Insurgent.
On the whole, I enjoyed Divergent. It's not as well acted or scripted as The Hunger Games, but it's still a fun movie and it didn't embarrass itself. That's not exactly a ringing endorsement, but I really did like it. The film had some issues, but it did a great job of showing that a Young Adult novel/film can be about strength and action and not just sappy love scenes. I'd recommend it and will go see Insurgent and Allegiant (which I bet they'll split into two movies...grr...)