My only criticism of this trade is the timing. Why now? If they could make this trade today, they could have made it later in the week. Why not wait and see if you can do better?
I'm not upset about losing Fultz, I'm sure he's a talented player, but so is whomever they get at #3, and neither would have a huge impact on this upcoming season anyway. I would have preferred any trade came with a player, especially a big.
BTW- regardless of the draft, the team building of the 2017-18 Celtics is FAR from over. So this trade needs to be configured with whatever happens the rest of this off season.