Celtics are definitely a very talented team, its a shame they suffered so many injuries this season, because they could've easily made the finals this year. I doubt they beat Golden State (I doubt anyone does, that team isn't even fair), but I could definitely of seen them beating the Cavs. Besides Lebron/Love, there really has been much production from that team in the playoffs, at least until recently. It took one of the most dominant performances in NBA playoffs history for Lebron to get by the Pacers in 7 games.
However, without Kyrie, Hayward, and etc, I can't see them beating the Cavs, Lebron is on a mission and its almost like he wants to prove a point that he can carry any team around him to finals.