I'm not sure it has to be better than OK. An undead patron is a rich thematic pool to draw from that's been utterly wasted by how mechanically lacking the Undying Warlock was. If we're taking this as part of a package deal with the Class Features UA from last year, then Animate Dead is already on the Warlock spell list and you've got everything you need for a classic necromancer.
But speaking of the Class Features UA, I note that nothing in the Undead Warlock specifically keys off Eldritch Blast. It's just "Hit a creature with an attack" triggers. So you could definitely roll a Blade Pact Undead Warlock, take the new Eldritch Armor invocation, grab a weapon, and start stomping around the battlefield as a heavily armored death knight swinging a necrotic damage greataxe.