There have been good video game movies, but the number is vanishingly small. Many are "so bad it's good" such as anything Uwe Boll makes, but there are a couple that seem to be created by directors who genuinely love the source material and take it in interesting directions (e.g. the first Silent Hill film, the first Resident Evil film, arguably Final Fantasy: The Sprits Within). Also, Mortal Kombat (1995) is a good…
Kinda cheating to call the Spirits Within a video game movie. It was titled Final Fantasy but was a wholly unique story and new characters and everything.
For another example, see Final Fantasy: Advent Children which is a sequel to Final Fantasy 7. It's pretty enjoyable.