It goes downhill with Blizzard ...

... While the game is still better than many others.
That reminds me of the multiplayer is too stressful for an RTS, I have only played through the campaign of the add-ons.
The story is quite acceptable and consistent, the atmosphere grip.
But what I absolutely went against the grain, was the time pressure. In almost any mission any Dünnpfiff one forces to act quickly, you have no time to enjoy the level, no time at all "strategy" applied.
Some call it creativity in level design, I call it, without this time pressure inability to create a reasonably challenging game. This has the final level shown good that comes without time pressure, one of the simplest of the whole campaign was.
But in its core business, the gameplay, the game, despite the limited time, been very fun. Also, upgrading the individual Zerg units has given me a lot of fun, so that remains a mediocre long, fun Zergkampagne for a reasonable price for me.