I understand that most people find the multiplayer more interesting, I just didn't think the changes HotS brought to multiplayer were that big.
Campaign mode has some really solid additions to gameplay, some well thought out missions (so far), and an interesting new story insight into the Zerg and Kerrigan. And Aigis.
Multiplayer has seven new units. Sure getting Lurkers back for the Zerg is great, but every other gameplay change was a per-expansion patch.
I'm not complaining, just surprised. I definitely wasn't getting this game to spend ten bucks on each new unit.