They compete with classic FFG, which I think have a worse price-to-performance ratio, but it all comes down to personal preference
Over time, your rival is left with no resources while Eldlich dominates the board
Gev helps keep the pressure on opponents with several abilities that support aggressive playstyles, and it's also a rare typing, with both Lizards and Mercenaries among the rarest subtypes in Magic: The Gathering (at least prior to the last few sets)
Most notably, Vampire Hunter and Vampire Scarlet Scourge draw inspiration from the whip-wielding Belmont clan and the dhampir Alucard, respectively
During your Standby Phase, as long as you don't have any Spell or Trap cards on the field, it can Special Summon itself back to the field
They aren't legal in anything other that the most casual of play, and don't have much value