Okay, d6 HP, maxed at first level, plus wizard as favored class, plus toughness feat, plus CON bonus. Result: First level wizard with 11 hp.
It was great to see in playtest! We had a wizard not afraid to move to attack position ahead of the fighters when he had initiative. It was like he was a vibrant part of the party, instead of some feeble old man who needed a wheelchair to get around.
That said, even goblins with tiny spears (d4) nearly knocked him down when the monsters went between the wizard and the rest of the party. In general, it isn't a MUST feat for the wizard, but he's getting mileage and running with it.
Add power attack, and you have the early build for Bigby. It's cool and not unbalancing to see a wizard that can actually hang tough in a fight. Now all we need to do is remind him that he does cast spells... Actually, come to think of it, it's a LOT like Bigby.