Now to serious stuff:
The characters are sort of well rounded and generally likable, but still hit on some of the tropes, namely being emotionally dead inside and lo-and-behold therein lies all your problems. Oh, and let's not forget that you have to have something to protect as well.
The animation is solid throughout the whole series except for one episode for about 1.5 minutes where it looks like the heroes are riding past a background painted on plywood.
One of the big problems is that very few things are fully explained, namely the Impurity stuff. So sometimes you have to burn it for incense, other times you have to boil it and drink the resulting water, other times all it does is cause hallucinations, sometimes it blows people up, sometimes makes a shockwave, sometimes it makes you strong, and sometimes it's just a pretty "poison" that noone properly explains. That's world-building spackle, kinda like how the Force can do whatever it needs to in Star Wars.
The plot's a little all over the place, and the lack of continuity makes it harder to engage in watching. If I were forced to watch it again (I hate re-watching or re-reading anything), I would do it at about one episode a day, because nothing about the ending of the previous episode really pushes me onto the next.
Another thing that's worth noting is that the ecchi is entirely arbitrary. There's no reason there couldn't have been more important male characters, the female characters couldn't have dressed in a more, either western fantasy or traditional anime, style and it would have sacrificed nothing. The last episode in particular was really the only ecchi episode, but I would say it was a fair palate cleanser after all the death, sadness, etc. from the story proper.
I do like that the female characters are strong (for most of the series), but when protagonist du jour discovers feelings again, she's essentially incapacitated for four episodes, and it get's really dull. However, I think that that leads me to my final point:
There might be some reference to the story of Buddha. After getting her emotions, Alka finally 'sees' the old, the sick, and the dead. Though I think the argument falls apart a bit when she goes on about actually living instead of being an ascetic.
Final verdict: Sure, go ahead and watch it. I'm sure you'd think it's around a 6 or 7 too. It was good for me just because I was running out of things to read and watch when I got home at night.
