If I'm not equipped to offer an opinion on the game because I'm critical of it (while still playing it) then neither are you because you're so clearly invested in the game that you're not going to see nor admit to any faults. I absolutely feel the campaign missions are too little and too short for the asking price. There is virtually no build up to the menace of the big bad of the expansion. You see maybe two instances of him fucking factions up, there is no sense that he is this inexorable, crushing villain. Instead you wreck his shit in a handful of hours. A few more missions to highlight why he's a threat would have been nice. As it stands it's over in the blink of an eye. I remember the vanilla Destiny campaign being longer and that cost $60 compared to the $40 for this.
Yeah I'm likely going to get a bit more out of it because I enjoy the multiplayer versus with friends but going back to the grind doesn't interest nor seem like meaningful content to me. Post campaign content that asks me to go do crucible matches or run generic patrols isn't a meaningful continuation of the story. Quests that ask me to create orbs of light aren't meaningful content.
After you've completed those missions which make up the main quest, there's at least 6-8 extra missions (not Patrol bounties, actual missions) tied to the different Taken War quest lines.
Also, the best 4 Strikes of the game.
Completing the main quest line + Taken War / Petra / Variks / Eris quest lines (some Patrol bounties and PvP challenges interspersed with actual missions) and all the new strikes is, in all, a denser, richer, longer, higher quality and more interesting package than the entirety of Vanilla Destiny.
And I know this is more an indictment of the game as it launched than anything else, but hear this:
I've been playing since day 1, and am not a casual player. Since TTK dropped I've played probably 7-8 hours a day, focusing on a single character (only unlocked new subclass on my alts, haven't touched them again).
I still haven't completed all the endgame quests, and I still haven't even touched the Raid, there's still some PvP modes I've yet to play (Zone Control, Mayhem Rumble), and I haven't even taken a look at Court of Oryx.
Cleaning out your Quests - even as a skilled player perfectly at ease with the mechanics, constantly informed of whatever strategies the community comes up with do do things more quickly, with serious overkill TTK preparation (I ranked my faction up 12 times to get new Legendaries), and an entire friends list of similar players to do the content with...I've put over 20 hours since Tuesday, on a single character, and still have a ton to do.
I know full well this game is not perfect. I myself am annoyed by it and there are a million valid criticisms of the game and its story. And value is subjective: this could be worth a dollar to someone else, whereas I'd have easily paid US$whatever for the fun I'm having with friends.
But as AAAs and their expansions go, this DLC and what it offers is certainly not a low bound outlier in terms of the amount of stuff to do it packs.