So what is wrong with RED2? Well, it suffers very heavily from Bruce Willis-itis. This is what I call it when Bruce Willis acts in a film and for some reason, always ends up with younger women. It happened in RED 1 for some reason, and it sorta happened in RED 2 as well.
So in R2, Bruce Willis must get the gang back together again to save the world. Except for Morgan Freeman cause his character's dead. People are trying to kill them again because of their past involvement with some secret experiment/mission whatever and now they have to fight back for their freedom. But on the way, they have to bring along Willis's totally useless and redundant love interest.
Which ends up with the film being less of an action film and more of a romantic comedy in disguise. Which frankly, kinda annoys me because the romcom parts aren't even good. Oh look Willis had another fling with another gorgeous spy a long time ago, watch the cat fight commence. Cue snarky comments about the other woman. Yada yada yada.
All in all, it feels very tired compared to the first film. The plot was a lot less cohesive and the scenes skip a lot. There's no real good narrative flow to the movie and the scene jumps are somewhat disorienting at times. It's like they went 'Oh, we need them to be here at this point' and bam, suddenly they are without showing the in-between.
Things I didn't like. Why is Lee Byung-hun AKA Stormshadow in the film? Or rather why is he USING martial arts in the film? It just didn't make sense to me, especially in the one scene where he was using martial arts to take down 5-6 cops while chained to a freezer and the cops had GUNS. Suddenly it seemed I went from watching an american action film to watching jackie chan in action. It just felt weird because the action scene basically went against the normal setting in the film. Sure, you do see Willis get into fist fights every now and then in the RED movies but it wasn't because he wanted to but more because he didn't have a gun with him at the moment.
Also, useless Love Interest. Seriously, her role is so shoe-horned into this film. Why is she even there? Oh, because later on she can seduce the Iranian diplomat into taking her into her embassy because after watching Bruce Willis pretend to slap her, he'll feel pity for her. Um..dude, wtf? First of all, how do we even know the Iranian diplomat would give a shit?
Then there's the fact that every goddamn sucker in the film knows how to fly a plane. By themselves. Including Anthony Hopkins character.
Overall, too many plot holes, bad writing makes this a pretty bad sequel in a lot of ways.