The Protoss campaign was ok. A lot of it felt like they just kinda had to come up with something because everyone expected a Protoss campaign. In fact, as far as Starcraft 2 goes, Wings of Liberty, IMO, is probably the most interesting campaign from a story perspective. Hell... take out all the Zeratul/prophecy crap and it becomes a decent enough conclusion in it's own right. The ending scene with Raynor and Sara was very strong... but then, thanks to the prophecy stuff and Heart of the Swarm that all gets abandoned pretty quickly and suddenly SC2 ends as a half-hearted epic.
Wings of Liberty - Rescue story
Heart of the Swarm - Revenge story
Legacy of the Void - Forced story