Aye. This is one of those animes, along with Suzumiya Haruhi and some others, that are really worth the hype.
Characters sharpened to strong fates and pasts. And they all have their own meaning and reason to be what they are. Elements like that are exactly what I want to see in stories. Well, the central idea of this show is for Yuuichi to remember his past (which means rediscover the multitude of girls of his womanizing past of course...). This has to be the best kind of harem anime you can have. Because it doesn't really feel like a harem anime at all.