If you had a person who's only played for 20h and a person who's played for over 100h who's view of the game are you going to trust?
Experience tells me the game was lacking and felt incomplete because I tried everything, I did the strikes, raid, story, collected the collectables and PvP.
After giving the game a thorough play through I came to the decision if this is what they gave me for £50 then I shouldn't expect much for £15 so it's not worth it. I could only come to that decision after putting all those hours into the game.
Tl;Dr
I played the game extensively I know the DLC is going to me just as poor as the main game in content story wise so there's no point in getting it.