While Blizzard doesn't usually set the bar very high when it comes to writing, this is probably their best work from a story perspective. Thoroughly enjoyed the campaign, not looking forward to waiting the next two (three?) years before Legacy becomes a thing.
I like how a lot of the concept art and promotional material was modelswapped Nova in for original Kerrigan when Narud pulled out that freaking sick Psiblade (where do I get one?). Unlike another game MGS2, I was honestly pleased with the result.
Of course, that whole build up towards the end was nothing more than emotionally moving. For once I'm very happy to say well done, Blizzard. Well done.