While some did hit the jackpot and land Sephiroth and other high-value mythics, most got burned with low-value pulls
Green Sun's Zenith flips this idea on its head by being a Turn 1 mana dork that is just as good (and perhaps even better) on Turns 3, 5, and 10
The reward you get for flipping Jerran is Ormendahl, the Corrupter, a reward that, while cool and powerful, might not feel worth the squeeze especially if it eats a Swords to Plowshares right after
No Undying for opponents creatures
Look at every card with Bodyguard here Bodyguard Rulings If you have two characters with Bodyguard who are both exerted, your opponent can choose which one to challenge
Although this is just anecdotal, I've also seen complaints on places like Reddit from players expressing frustration over grades received on certain cards