In a world where magic and anti-magic, and maybe even Dispel spells, exist for a long time and practitioners of each has adapted ways against the other, it's actually a perfectly viable ability to have.
In a world dominated by magic, the presence of anti-magic as an OCP that the magic-using protagonists struggle to overcome is meh. It's doubly irritating when the writer also give them extra resistance and/or survivability against non-magical attacks, and supremely infuriating with regeneration added to the mix, creating a blatant Mary Sue/Villain Sue.
It's also annoying when the anti-magic not only cancels the spell, but also all the environmental effects and collateral damage. For example, anti-magic that not only killed a fireball spell but also inexplicably and conveniently put of the fire instantaneously before it can damage its target. Also extra annoying when their magic-using enemies keep insisting on direct attacks instead of getting creative with their powers like using telekinesis to throw hard objects or collapse the building where their target lives or sink the ship they're in...basically anything beside futilely firing magic directly at the anti-magic source.