Plus/minus is a bit of a controversial stat. Certainly it needs to be treated with care, because of issues such as quality of opposition, team strength, empty net goals, etc. However, there are many hockey fans who would prefer to throw it out entirely for these reasons.
What is interesting to me is that many of these same people will rely heavily on goaltender wins to evaluate a goalie. Wins are determined by goals for and goals against, so goalie wins measures whether there are more goals for or goals against when a goalie is in the game. That is conceptually similar to plus/minus, the only difference being that a goalie really only has an impact on results at one end of the ice, while a player can go both ways.
So why do many hockey fans rely heavily on goaltender wins to evaluate a goalie, which is basically a measure of the goals for and against while a goalie is in the game, and yet completely reject plus/minus, a measure (however imperfect) of the goals for and against while a player is in the game? Doesn't make sense to me.