The manga is also entertaining, although sometimes the author just seems to totally forget what story she's trying to tell. Things get quite dramatic and dark as the story goes on.
The anime does not actually have an ending, as the manga had not completed by the time it finished up, so they just left it a bit open. Really this is fine, it happens all the time.
As for the manga, as of chapter 170-something of the manga, there was a long hiatus, and when the series came back, the artwork style had changed DRAMATICALLY. So, if you commit to reading the whole series, be prepared for the art to change around that time. I'm not sure if I would say it decreases in quality, but it definitely does not look like it's still being drawn by the same person.
