Healer as a feat is amazing in the hands of a Rogue (Thief) with the Fast Hands ability.
Healer Feat: "As an action, you can spend one use of a healer’s kit to tend to a creature and restore 1d6 + 4 hit points to it, plus additional hit points equal to the creature’s maximum number of Hit Dice. The creature can’t regain hit points from this feat again until it finishes a short or long rest."
Healer's Kit: "This kit is a leather pouch containing bandages, salves, and splints. The kit has ten uses. As an action, you can expend one use of the kit to stabilize a creature that has 0 hit points, without needing to make a Wisdom (Medicine) check."
Fast Hands: "Starting at 3rd level, you can use the Bonus Action granted by your Cunning Action to make a Dexterity (Sleight of Hand) check, use your thieves’ tools to disarm a trap or open a lock, or take the Use an Object action." (the object being the Healer's Kit to spend one use of it to tend to one creature as a bonus action).
I believe it's gotten affirmation from one of Mike Mearls or Jeremy Crawford, but apparently using Fast Hands with the Healer feat, you can in fact restore 1d6 + 4 +HD hit points to an ally with a bonus action during combat, once per short rest. That's pretty darn powerful.