Was it even appropriate to make this movie before the case goes to trial!? It would appear that the American Judicial system continues to merge with the American Entertainment Industry such that there is very little to distinguish one from the other any more. So my short answer would be, "Yes it probably was appropriate".
As for the movie itself, I'm impressed with it's attention to detail and how well this made-for-TV movie stands up to multiple viewings. It's essentially just a chronology of highlights leading up to Scott Peterson's actual arrest. Portraying Scott as perhaps innocent would be a nearly impossible tasks just looking at those rather damning events. To get around that dilemma the producers use the purposely gullible character of Tommy Vignatti to convey the outside possibility of Scott's innocence right up until the final scene of the movie.
All the performances by all the leads in this movie are completely believable and they all do an excellent job of showing how those immediately involved went from initially supporting Scott Peterson to one by one viewing him with distrust and disbelief. I would give this movie very high marks for the type of expositive TV drama that it undeniably is.