Could we have a summary? What’s wrong with it?
This applies to both EK and Bladesinger, as they are two sides of the same coin.
Essentially they're both less fun, less unique versions of the 3e duskblade, 4e swordmage, and pathfinder magus, with what made those classes interesting removed. We had a great half caster template for 5e classes, and instead what could have been a fun class got relegated to a pair of subclasses. Which in turn prevents a proper class for it existing.
Both paladin and ranger get unique spell lists designed around their playstyle. Meanwhile the EK is glued to the wizard list, which isn't designed around hitting things with weapons at all apart from two cantrips. Paladin and Ranger are getting tons of levelled spells like searing smite and ensnaring strike to set their sword on fire/ice/thunder and smack things. Which basically emulates the spellstrike ability which duskblade/magus/swordmage were known for.
The result is that if you want to play an arcane swordmage from prior editions, you're better off asking your DM to reflavour a paladin, ranger, or hexblade, than to actually play the arcane swordmage subclasses in 5e. Their thematics are utterly wrong, but at least they play very slightly more like those classes once did.
If 5e is your first edition of DnD and you don't have the others are a comparison point, EK is a perfectly good subclass without many issues. If you've played those prior edition/pathfinder classes and want something like them, then EK is worse than useless for it.
Honestly just adding searing smite, thunderous smite, ensnaring strike, and the other similar spells to EK would partially fix it for me.