I recommend it, but keep in mind that at it's core it is a love story. Maybe read a review or two beforehand.
The explanation of the time leaping is a little weak, forced, and random, but (surprisingly enough) the time leaping isn't all that important to the overall story. It is the characters that matter and they are ALL very likeable.
The main character especially. She is charming, a little hot-headed, but so clumsy and good-natured that you can't help but like her. Her opening dialogue is great. It is all about her being "lucky most of the time" when everything that is happening to her is VERY unlike. Haven't we all had those days?
The movie is very funny as well, and it gave me fuzzy warm feelings about highschool that I never thought I would have.
It isn't very action oriented, but it has good drama, great animation, hilarious and genuine characters, and overall is a very well made film. I personally recommended it.
The ending too is great. Despite change, life goes on and we should accept that change and welcome it with open arms. Even go out of our way to make changes in ourselves. After all, nothing stays the same forever.

That is what I got out of the ending...
And if you do buy it and like it...watch Summer Wars...made by the same director as The Girl Who Leapt Through Time and is even BETTER then this movie.