Watch it for the character development.
I haven’t read the manga yet, but I’ve watched the anime twice, once as a 14-year-older (way too young an age to take it in properly) and again fairly recently (I’m turning 23 in ten days). Knowing that the series, probably expecting to produce another season, left more questions open than Neon Genesis Evangelion did, I knew not to expect a lot of answers. So, my advice would be to watch it for the character development Ritsuka undergoes, which is handled very well, as he learns to become more sociable and stand up to what he’s ‘fated’ to be and do (same goes for Soubi); he comes off, to a certain extent, as Shinji-lite, someone Westerners could relate to much better. Yuiko, initially a somewhat obnoxious crybaby, quickly shows there’s more to her than meets the eye and becomes a watch-worthy character. The Deconstruction of the romantic ideals of fated couples and Undying Loyalty and unwavering dedication is also handled very interestingly and is very well done; the series’ 12 episodes are enough to develop these themes exactly at the pace they should be. The directing falls every now and then to some anime clichés it shouldn’t, certainly not in 2006―overly slow motion sequences (particularly in amorous situations), lovers surrounded by flowers like in shoujo manga, somewhat Narmy battles―but these quickly take a smaller place in the series, and other wise directorial decisions really show, most notably the music selection. There’s some Values Dissonance in the series regarding intergenerational relationships, but this lessens a bit when you notice people there don’t bat an eye at a teacher hanging out with her students, so you can assume people assume the best about Soubi and Ritsuka’s relationship, and enjoy some Values Resonance at Yayoi being an entitled creep and repeatedly getting rejected the way he ought to (Yuiko being more upfront and unapologetic about rejecting him is also very pleasing to watch). All in all, it’s not a perfect series, but if you watch it for the right reasons, it actually makes for a very enjoyable and satisfying watch. 9/10