I cannot find any reason to call this rebuild a smashing success at this exact moment. Since that was the question, I say no. I would also say no to this being a massive failure if the question were reversed.
I think Grier has made some good moves, some bad moves and some whatever moves.
We have not even had a single one of his draft picks play in the NHL yet, and considering the draft is the most important factor for whether this rebuild is going to be a smashing success or not, I fail to see why it would be deemed as such already.
He has wasted picks for players, there is plenty of argument about the returns he got for certain players, a lot of his player pickups have been either completely useless or bad. However on the other hand he has gotten a few 1sts for us, some of his player pickups have been either fine or a pleasant surprise, and while he has wasted some picks for players they've all been mid/late round picks which hold very little value.
In short, I think Grier is doing fine, but would not qualify it as a smashing success at this point, its simply too early to tell.