Replaying the LotV campaign. Oh man.
1. The story is truly abysmal. Like holy crap. It feels like a terrible anime.
2. I still hate Alarak. I don't understand the appeal of Alarak. He's a joke. Everything he says is just like "Darkness! Evil! Love is for the weak! There is only power!" It's like if some fourteen-year-old kid decided to splice their Shadow the Hedgehog fanfiction with Starcraft. People say "But he's like the new BW-era Kerrigan!" Nope. I just played Brood War, and I sure as hell don't remember any monologues about "LOL evil is teh coolest!"
3. I also hate Artanis. I have always hated Artanis. From the very beginning of Brood War where it's like "Okay there is no way in HELL I was this goofy-ass drama queen in Episode 3." But here he's even worse. I feel like he's got a speech impediment where he's unable to speak without making a pompous and grandiose speech. All Protoss are like that, I guess. Just Artanis is way, way worse.
4. The story is unintentionally hilarious in the best way. Because Protoss don't have facial expressions they just have the camera do a really quick extreme close-up on Artanis whenever he's surprised or upset about something and it's amazing(ly awful)
5. In spite of all this, they really outdid themselves with the gameplay on this one. This is, by far, the most fun and most challenging campaign I've ever played in an RTS. The second time through the same-y mission objectives didn't bother me at all. The "Destroy 5 Macguffins" thing is really, really good. Why? Because it forces you to get your army outside of your base but prevents you from dedicating much time to destroying the enemy base. It works especially well because they seem to have taught the AI to hit your base hard after your army moves out (or to just hit you regularly enough that it doesn't matter). And the army composition they send at you is usually on point - enough so that you typically can't rely on static d to hold them off for long (unless you micro it, I guess).
See, to me, the greatest irony of LotV is that it actually has some pretty awesome emergent storytelling. The relative difficulty of the campaign combined with the bombastic soundtrack can create some pretty tense and dramatic moments. Then suddenly you're sucked out of it to endure cheesy, hackneyed cutscenes about the Dark God coming back and Oh No.
Also, seriously Blizzard? You introduce a powerful new robotic unit with the expansion, you have a plot point where in the campaign you uncover the Purifier project to gain powerful new robotic technology, and we don't get the new unit? Like, what the hell? This was an amazing opportunity to be like "Yeah here's the Disruptor, go wreck shit" but instead we don't get that at all. I mean you did bring back the Reaver so I'm inclined to forgive you, but for real.
EDIT: I should, however, clarify that the campaign becomes much easier towards the end, and mass Void Rays make several missions quite trivial. I always sub out Void Rays for Arbiters because lol nostalgia, so that ups the challenge a fair bit. Nonetheless, expect the difficulty to decline as you go further along.