I'm actually quite optimistic because we matchup well with them defensively at every key position except the 4 spot. Smart vs Irving, Bradley vs Smith, Crowder vs LeBron... We have no one to guard Love properly but I think he will underperform (just a gut feeling).
However I don't think we will pull an upset because I fear we might struggle mightily on the road, the playoffs being a new experience for the vast majority of our players. The Cleveland crowd should be ferocious for the first two games, so a lot depends on how we handle that. I also think that, ultimately, our lack of scoring will kill us : even if IT performs well (and I'm sure he will) he won't get enough help.
In the end, I predict 4-1 or 4-2 for Cleveland. I will go for 4-2 because I think the Celtics will surprise many once again by showing some wild toughness and great coaching by Stevens.