I don't think it's an exaggeration at all, but I'm glad you enjoyed it as much as you did. I'll still play Heart of the Swarm, but I won't be anticipating it as much.
I'm pretty sure that's going to be subjective. Anyways, my primary comparison was obviously going to be SC1, which I thought was *much* better for its time.
I think the story and the story presentation were much better with SC1. They actually gave a damn and did surprisingly well given scarce resources.
However, the vanilla campaign is good but not fantastic. For the most part, you just build a base and eradicate the enemy. The "control-a-few-units" missions are terrible in vanilla, but there were a few other good ideas.
Brood War, on the other hand, had a -great- campaign. I guess if anything bests SC2, it's Brood War. Lots of variety. Lots of fun. Even the "control-a-few-units" missions are great, except for one or two. On top of that, still a great job telling the story with such minimal capabilities.
That said, I've played a bunch of other RTSs. I really don't think the others are on the same playing field as either SC in terms of single-player campaign. For that matter, ditto with modding and general multiplayer mechanics. SC2 lacks chatrooms and LAN, so that's an issue. On the whole though, the system still seems a significant step up from Dawn of War 2, which is probably the closest competition.
Still, like you said, it's all subjective. People enjoy what they enjoy.