My humble opinion: This is one of the best SciFi movies ever made! I was a loyal fan of the TV series “FireFly” … and this DVD is a fitting tribute to Joss Whedon's masterpiece. The movie satisfyingly ties up many loose ends that were left unanswered in the TV series. I always felt that the character of River Tam was very undeveloped in the TV series (because they were hoping for further seasons of Firefly being made I suppose). Anyway, Serenity certainly delivers on that score, River is finally revealed to be something very special indeed.
Great story, emotionally involving, great character development, action, special effects (not overdone either). The movie is a great adventure from start to end.
5 stars from me.