Yeah, that was my main sticking point, £40 is a bit of a piss take.
From what I've seen so far I'm okay with paying what I paid, but I can understand why lots of other people wouldn't be.
For what it's worth, I've played through 5 or 6 of the new story missions, and it actually goes back to taking a page of Halo's book and having proper cut scenes that explain a story this time around. They've given the people in the tower a bit of personality now (Cayde-6 and Eris Morn's conversations are hilarious, sometimes intentionally, sometimes unintentionally), and the game just feels like a more rounded experience now. Plus the new Taken enemies are great. They look cool, they provide a new challenge, and they're not just bullet sponges like so many of the earlier bad guys.
Kinda peeves me though, because essentially everything for the last year has been a kinda beta test ready for year 2 to showcase Destiny properly.