This is awfully close to being a 2/2 for B with no drawbacks.
If blocked, the opponent still loses 1 life, which makes it somewhat better than a vanilla 2/2, but it can only do 1 damage to a blocking creature, which makes it somewhat worse than a vanilla 2/2.
If blocked, the opponent still loses 1 life, which makes it somewhat better than a vanilla 2/2, but it can only do 1 damage to a blocking creature, which makes it somewhat worse than a vanilla 2/2.