No spoilers except: MUWAHAHAHA! I was right!
ANYWAY!
All in all, I give this series a pretty solid thumbs up. As much as I like it as an idea, I tend to give a lot of the "girls with guns" anime a pass, as they tend to be an excuse for rabidness and extreme fanservice. There are a few fanservice moments here, but not too many, and the character designs are pretty understated and respectful, even when they do show some skin. In addition, Madlax herself seems designed to be a little more muscular than the other chacters. It also has a wide variety of female characters, both fighters and otherwise, all of whom are pretty well developed and easily identifiable.
I can't really think of much to say that isn't purely spoilery that I didn't say in my first post, so I'll just skip talking about things like plot. While my capslock squee is probably noted for being set off by every little thing (it really isn't, I just try to only read/watch things that will set it off!) I should note that it was out in full force through most of the series, as most of what could set it off was present. Take that as you will. It can be slow in parts, and you have to pay attention, but it's worth it. In a lot of ways, you're better off not really thinking about it and not trying to figure out what's going on, as you'll just give yourself a headache and start missing things. It comes together on its own as long as you pay attention.
It does tend to randomly introduce interesting little quirky things that are never explained, such as why Madlax will randomly change into an evening gown for battle, but those somehow only cause mild amusement, not irritation. Also, the soundtrack is amazing and at least part of the plot revolves around Sooper Speshul Books. See the "capslock squee" part above.
And now I must hunt down the other parts in the studio's "girls with guns" series.