There were some enjoyable levels. I think one factor that soured my impression of the game in general is what I'm going to call 'a liberal portion of awesomesauce' for lack of a better term, and by this I mean that the cheese level at times was turned up to 11 for the sake of getting fans to utterly wet themselves and drive up sales, especially in the cinematics that were released to introduce the game. Also, as I've said before, it pissed me off how overall I'd say that at least 75% of the cinematic material introducing the new game before release were from recycled footage, the final one had an all-time-low (for LOTV) of approximately 50% recycled footage.
If the main LOTV campaign had been the end, I would have thought, "that was the most unoriginal and bland conclusion I think I've ever witnessed". I would liken it to Matrix 3 except that film/overall plot was bland and extremely flawed (ie. "WTF? None of this made any sense")
The epilogue helped considerably, and IMO the epilogue should have basically been most (or say half) of the plot of LOTV rather than being relegated to 'almost an appendix'.
The characters in LOTV were total cardboard cut-outs, which isn't necessarily an issue but it becomes more apparent when other facets of a production are lacking. IMO the plots of WoL and HOTS were better because the main character's motivations were simpler. Simple motivations are easier to conclude. I never did get a chance to murder the extremely irritating Tal'darim character (in a way that may or may not have inadvertently turned him on), he wasn't quite as irritating as Jar Jar Binks, but if he had thrown in some sort of S&M reference as well as his uber-evilness I think I would have rage-quit the game. The fact that another Tal'darim character (evil of course) had 'Mal' at the start of his name is yet another testament to how crudely written this plot was.
There's one level later in the LOTV campaign (the penultimate one, not including the epilogue here) which had an obvious plot hole in it, like glaringly obvious - the player spends x amount of time on the surface destroying ground forces in order to destroy protective thingmejigs so that Amon's physical body can be destroyed, then the cut scene has the Protoss doing an orbital strike to kill that body. Why didn't they do that to begin with (ie. destroy thingmejigs and body with an orbital strike)? The orbital forces were literally doing nothing at all at the time.
The final LOTV mission (again not including the epilogue) wasn't absolutely identical to the final mission in WOL, but it had exactly the same objective.
One thing that really got my goat (less so in the epilogue but it's still pretty bad) though was how allied CPU-controlled forces were beyond lame. Sometimes it was like trying to play against multiple opponents that are about as capable as I am, but my allies had barely played SC2 before. I can understand how these allies can't be too capable because the game would become too easy, but perhaps doing things like them using a clever tactic from time to time, which if the main player notices, they could exploit and launch an offensive, or at least something interesting that might advance character development.
Something else that really got on my nerves was how when the epilogue started, all the customisations I had made to my forces were lost and it seemed like I was stuck with some of the worst combinations of Protoss forces.
One thing that I would be at a loss to explain though is Amon. Why did he intend to kill all of the Xel'Naga? How did he manage that? Didn't any of the other Xel'Naga notice that he was a douche and anticipate such a tactic? What's his motivation in this universe? If this universe can interact with the void, have any others? Why was Amon apparently only interested in this universe? From what I can see he's just a villain cliché that needs to be there because otherwise there wouldn't be a trilogy and WE MUST HAVE TRILOGIES.
Another thing that really gets my goat is that apparently a lot of time was spent in the short stories that one can read on the StarCraft site. Minor characters with some depth of character, their own motivations, plot detail adding to the richness of the story... why wasn't any of this built into the game? Instead we've got "goodie humans and baddie humans", "goodie zerg and evil zerg", etc. You're either good or evil in this universe, there's nothing in between. Horrendously lazy writing.