"Toki wo Kakeru Shoujo" was originally a novel, first published between 1965 and 1966, from which sprang a plethora of different adaptations: four dramas (including this one), four movies, a stage play, a manga and a world-acclaimed and überfamous animated movie, ten years older than this drama.
Now, the big problem with doing the Nth adaptation of such a famous story is that you risk either being too faithful to the original (and/or to a previous adaptation which got even more famous than the original, as it might've been the case here), thus resulting bland, unoriginal etc....or else doing just the opposite, that is, adapting it too freely, changing too much and therefore ending up enraging the fans.
That's why taking up such a challenge ain't no easy task, and I'm sorry to say that imho the screenwriter didn't do such a good job. The story manages to be more faithful to the original book than to the anime in some parts, and that's kinda nice...but then the too many new elements felt unnecessary and detrimental to the overall quality of the script. A coupla side stories showed potential, but were way too short due to the drama having only five episodes (which begs the question: why bother with side stories then?). All in all, I'd say it felt as if the author tried too hard to please the modern public's tastes (real or perceived).
The cast did well, and the "packaging" is the best aspect of the drama: great direction, editing and photography, lovely scenery, nice music.
You'll probably appreciate this more if you've never read or seen the original or one (or more) of its many adaptations, imho.