This has been literally the worst event in the history of League.
I could complain about how the missions have very low rewards in comparison to the prices of the items, or how they're made to be deliberately time consuming, to convince people to just buy the items instead, but that doesn't really bother me. Riot is offering free content, I'm not going to complain about the way in which they offer it.
What DOES bother me is the kind of gameplay the missions have been encouraging. People show up in games and never join teamfights, only to say "I'm just here for the quest". Or they'll constantly throw themselves into teamfights head first hoping for a kill, stealing every kill possible from teammates, and not caring if they die, because they have a quest for kills. I had to go to ARAM to find people who actually wanted to win a game. It's hard enough to find people who legitimately want to play the game in the first place, players shouldn't be incentivized to sabotage matches.
On a side note, saying the phrase, "Who cares? it's normals" should result in an instant suspension.