What sucks about Jak II's story is its characters. First, they try to make Jak a badass. How do they do that? Torture him for two years! That'll make anyone cool! Not only that, but apparently it gives him a gruff voice and muscles! Then you meet a team of people trying to save the city, but GUESS WHAT! SOMEONE IS ACTUALLY TEH BAD GUY!!11!
They try to include two love triangles: One with Kiera, Praxis's daughter, and Jak, and the other with Jak, the rebel leader, and Praxis's daughter. Do either of them get resolved or go further? No. Because that would have made at least some of the characters interesting, seeing how they'd react to each other in those given situations, but we're only treated to one cutscene each regarding those conflicts. Weak.
The whole idea of Haven City was nice, but poorly implemented. I can't remember the last city I went to that was actually a maze. People get pissed at The Wind Waker for sailing, but this has the same problem, maybe even worse because there are NEVER any warp switches to get to the other side of a city ever. It's kinda confusing considering we're in the fucking future, and there were warp points in Jak and Daxter.
The vehicles sucked. I don't care about realism. This is a fucking video game. The main character gets dark energy and turns into a Mos Eisley resident. Who cares if the vehicles don't respond like in real life?
About the secondary characters/villains like Krew and Praxis: I didn't ever hate them. I actually felt sorry for Krew because he was the only character who did feel developed and ND killed him off.
The humor was good in this game, so I liked Daxter and Pecker, along with Phil Lamar's character's "death scene."
The boss battles were weak though. Jak and Daxter had some interesting stuff, and the boss fights against Praxis in Jak II were good. I just couldn't believe how poorly handled the fights with Krew or the Metalhead leader were. It was amazing that the final boss was so basic. There was no strategy (except run and shoot) or anything fun about it.
The plot twist at the end was well done, I'll give ND credit for that.
I've got more complaints regarding specific characters and gameplay, but I'll leave it alone for now.