1. I hate Worf, and TNG Klingons in general. Worf's sole purpose was to get beat up to show how tough the alien-of-the-week was. The TNG Klingons had a one-word vocabulary: "honor". They were thrown into that mindless rut and never emerged for the entire rest of the franchise with the brief and refreshing exception of the Augmented ones in ENT. This is the reason I hate Worf in DS9. He switched from impotent growler to honor-lecturing bore. Klingons are supposed to be mustache-twirling villains, dammit!
2. I think the Temporal Cold War would have been a really cool idea if they had actually gone ahead and done it instead of just half-heartedly referring to it a few times and then forgetting about it completely.