I just finished the campaign on hard.
Overall took me ~11 hours to finish, i was doing it on HARD mode, and was trying to do some small achies along the way (so i did reload quite a few times).
Have to say, really dissapointed with single player. Especially with the story. I absolutely loved the original SC story, and quite liked WOL story too. HOTS story feels like they just threw together 150 different writers and told them to write something tangently relating to zerg.
I mean, zerg dont even feel like zerg anymore. More like... biological terran or something. Philosophical discussions, independent thought, etc... What happened to my swarm?
At times story makes no sense whatsoever, and the gameplay isnt that much better either - i really am tired of the "What, did you decide to push out of your base? Here, lets have a squad of 15 tanks spawn outside your base with no warning of any kind. Have fun running back half across the map".
I know SC2 is mostly about multiplayer - and MP HOTS is very, very good. However, i dont think i have ever been so dissapointed with a blizzard game as i am now with HOTS singleplayer. Well, except maybe cataclysm.
Time to sleep now. Wish i did that instead of staying up to play this.
Edit: i Brutalled the WOL campaign and loved it. So its not me being terrible. I just really, really dislike HOTS.