I dithered about getting this for ages - I like time travel stories and this one intrigued me but I wondered if it was also suitable for my 6-year-old daughter (we have watched many Studio Ghibli titles together). In the end my wife got it for me from my Amazon wish list.
From my point of view I really enjoyed the film. It's not outstanding and I'm not sure how it will bear up to repeat viewings, but I'm glad I got it. And at £3 it's a bargain. It's not up to the standards of Studio Ghibli, but then most things aren't.
Generally the animation is very impressive, although there are a few almost static shots that linger on the screen for too long.
As for possibly adult themes - there were two 'j*rking off' references (well, technically one I suppose as the same piece time was played out again). One boy suggests another is late for school because he was too busy j*rking off, or something like that. But it's a fleeting reference and passes without comment. The other bit of language was someone saying they were 'p*ssed off'.
Both of these did seem a bit out of place, considering the rest of the film is so innocuous in terms of language. Perhaps it's a translation issue?
The story I suppose is quite 'grown up' in the sense it's about a young girl growing up, learning responsibility, discovering how she feels etc. However, my 6 year old enjoyed it at her own level, a story about a girl who could time travel. The mild language passed over her head.
I'm glad I got this film. It didn't turn out to be as clever as I expected, but it was still an enjoyable afternoon on the sofa with my daughter.