I'd hedge the offense more towards a B-/C+ due to the lack of execution that he noted but overall, I'd agree completely with his grades.
I'd probably say a B overall.
Defense was an A-. If not for a key turnover, this could've dropped to a B, but to hold a team to 10 points, you're in A- territory. Single digit scores are needed for an A, unless you're playing against an offensive powerhouse.
Special Teams was a B. Good, not great.
Offense I'll give a B-. I liked the run game, but the caveat being Atlanta's run defense. In the passing game the protection was excellent, but the execution everywhere else was inconsistent. If Galloway doesn't run out the back of the end zone, Brady doesn't overthrow Moss a couple times, and Edelman and Galloway catch some of those drops, this can become a B+ or an A very easily.
But overall, they get a B. They played good enough to win, and win by a couple scores, but there is still a lot of room for improvement.