I think people are exaggerating about those mage cards. That 2 mana control spell is a perfect tool to any no minions mage deck going forward. Pretty much an auto-include, and no minions is pretty much guaranteed to be good at some point in the next 2 years. It has 5 sets of new spells to wait for, some of which might support the no minions condition too.
The frost copy spell is fine, better than Reverberations in some contexts and sinergies, worse in others. For 3 mana you stall a minion and summon a full copy of it that your opponent has to deal with or else you attack with it next turn, possibly trading it into its copy. Is that a bad card? Don’t think so.
The casino minion isn’t bad either. You likely won’t put this into a deck but you will see it summoned off Spot the Difference very often. You’ll be surprised by how much value it can instantly generate if not dealt with.
Are these the best cards imaginable? No. Are they bad? Don’t think so. It’s probably gonna be middle of the pack in the overall miniset. I don’t think it justifies getting worked up about it. Minisets don’t often bring stuff that instantly click entire archetypes together, like they did with hunter. They usually bring some useful, standalone tools to work with.