Love Hina's story won't win any awards for originality or pushing the envelope; it plays very safe and has a very saccharine backdrop; it's not like a character fulfilling a promise to his childhood sweetheart hasn't been done before. Where Love Hina succeeds is pulling it off with such heart, and only touching on it lightly right up until the last few episodes.
Most of the time, the show focuses on the characters and their relationships within Hinata Apartments, and the zany antics they do to keep from getting bored.
The characters, as you'd expect from any harem series, form the spine and take the central role in the story. Each has something to contribute in their own psychopathic, borderline sadistic way to keep the show lively and fresh (Mostly in the form of abuse towards the lead, Keitaro).
Keitaro himself is an increasingly likable lead character for all the torment he's put through at the hands of the tenants of Hinata Apartments. His devotion to the girl he made a promise to almost 20 years before the main plot and his determination to get into Tokyo U, even after repeated rejections, is almost enough to completely excuse his bland personality and appearance.
In the animation department, the show doesn't fare so well. It's workable throughout, and usually does a good enough job at keeping up with the often frenetic pace. However,the occasional slight hiccup or static background doesn't impress. And the characters, while distinctive, aren't the best looking. After all, I can't be the only one who thinks there's something wrong with Kitsune's hips. The art itself is good for the most part (Again, Kitsune's hips detract somewhat), but the occasional glitchy animation is too noticeable not to mention.
Where the animation stumbles, the sound props it up and carries it to the finish line. Everything, from the exceptional voice-work to the quick paced and cheery OST, is imbued with enough life to wake the dead within a ten mile radius.
Despite all this, Love Hina has its share of faults. The characters have a good possibility of annoying the viewer, some of the plot points feel needlessly contrived (Though the most humorous ones are generally acknowledged as such), the abuse of Keitaro can feel downright sinister at times, and it can overstay its welcome if marathoned. However, looking past these, it's easy to see why Love Hina is considered a borderline classic. It has enough quirks and outright bizarreness to entertain, supported by a charged pacing that gets the blood flowing.
Love Hina isn't perfect, but very little of it, aside from the robot turtles that crop up from time to time due to the machinations of Su, feels manufactured. It's of an authentic high quality, and well worth the time to watch.