It's enjoyable only if you really like the "Back to the Future" universe, as you have your favorite characters back, in an new adventure that even works as a 4th episode/movie. However, the game can become very stale and boring from time to time, and some puzzles are a little annoying to solve.
In the other hand, the voice acing and character animations are wonderful, and the end of the game (all of the final section) is pretty cool.
But as I say, I recommended it only for fans of the series.