YMMV / JLA Exterminators

• They Wasted a Perfectly Good Character: Most of Ian's fellow new metahumans (Nigh-Invulnerable detective Bryan, pyrokinetic Country Mouse Julia, the grieving mother who makes a golem, a doctor with Healing Hands, the teenaged teleporter, the clairvoyant retiree, etc.) have cool powers and have powerful interactions with JLA members who either fight alongside them or are sympathetic to their situations. It would have been interesting to see the team fighting to save all of them from mutating along with Ian (or have more progress in trying to cure specific mutants whom they'd bonded with) throughout the whole book. Unfortunately, none of them make it to the final act, and those who mutate are barely, if ever, mentioned by name afterward.
• Unexpected Character: The original Young Justice team roster makes an appearance even though their series had definitively wrapped up (with some of the characters retiring from hero work) over a year before this book came out.