Yea, now that I've gotten a few of the new ones, I can say it doesn't quite feel worth it for 50g. They feel not quite twice as hard to complete as most 40g quests. I think most of them should have been worth 60g and then we'd be happy. Had the 10 divine shield quest today and even after making a paladin deck with like 12 divine shield minions, it still took 3 games to finish. I lost first game too quick, only got 2 down, then I won the 2nd in a very long game against a reno warlock that got reno off at 3 life when I had easy lethal. He also healed for like 10 off other things (brann + earthen ring farseer, etc..) So, I did 60+ dmg to him in a very long game, and only played 7 divine shield minions in that super long game. Had to play one more just to get the 10th one.
Sure, I only played 3 games to do it, but it was in the casual queue, it was one of the easier ones to do, and I still had to make a deck dedicated towards finishing the quest. I would have rather played 5-6 games in ranked and just easily finished a quest while I was doing so. Or, since I play more arena then constructed, just played an arena run with a certain class that I had quests lined up for. Most of the time, I can stack 2 quests over a day or two for a certain class and wait till I get that class as an option in arena.