Yes a large portion of foes - elementals, undead, celestials, fiends, fey, and aberations. It certainly varies by campaign, but that is 44 pages of monsters on D&D beyond out of 138 pages total. In addition to the disadvantage on attack rolls, it also completely nullifies frightened and charmed from those creatures (assuming you cast it before their turn). These are two very debilitating conditions on a melee combatant, frightened completely stops movement towards the enemy and charmed stops you from attacking them. That is in addition to other effects that often come along with these conditions when imposed by an enemy (incapacitated, controlled, must run away etc). It turns an encounter from something like a Chain Devil from a very tough fight to a walk in the park for a tier 2 fighter.
IME, it is the second best EK spell after Shield. It is more useful than Absorb Elements, which I would say is the third. All three of those are abjurations and none of them require intelligence, making them ideal on an EK.
A 3rd level EK has two spells to pick from this small list, and a 4th-6th level EK has three spells to take:
Absorb Elements
Alarm
Mage Armor
Protection from Evil and Good
Shield
Snare
Burning Hands
Chromatic Orb
Earth Tremor
Frost Fingers
Magic Missile
Tasha's Caustic Brew
Thunderwave
Witchbolt
What spells would you pick from that list instead of the 3 I mentioned?
If you are running a high intelligence a few of them are decent options, but even those are very situational as these are 1st level spells without slots to upcast effectively, none are good controls spells (even when compared to other 1st level spells) and they are not going to do a lot of damage for this level or any future level.