HOTS was a welcome surprise for me. It really helped rekindle my desire to play Starcraft again. While the story seemed a bit contrived and forced, the addition of the abilities, the great models for the main characters, and the gameplay really pushed the campaign forward.
Could have used more of an introduction to the Zerus arc. Primal Zerg is a great idea, I just wish they were more wild as the dialogue suggested. About the roaches, etc.: it is said that they quickly evolved their own versions of the current units after the first couple of battles and taking their essence.
Also a certain returning fan-favorite/fan-service character explains his whole back story in his aggravated responses from clicking, making light of the fact that he's even there at all with his rundown. They were obviously trying to throw in some more humor, but it seemed a little too silly.
Also need more missions like the Hyperion, even if just as an Arcade game, that was a nice change of pace and with some tweaking could really soar in the right hands.
Now if I can get back into playing some competitive games... Just do not have the time to commit to it at the moment.