I feel like Hex and/or Agonizing Blast (which would require taking another feat: Eldritch Adept) are mandatory in order to make it worthwhile. EB is at least partially regarded as such a great cantrip because Warlocks can get the Invocation: Agonizing Blast to add their Cha mod to its damage. Otherwise, you basically have the same thing in firebolt, except for the damage type and firebolt's single-but-powerful ray vs EB's weaker multiple blasts...
Though quickening and then normal casting eldritch blast, especially at level 5+ for 4+ beams per round, does sound fun.
