First things first, I used to like this manga, I actually still prefer it more than Rave Master, but that is just my personal opinion. I found the characters to be somewhat interesting at first. Hell, I watched through some of the arcs (Never exactly finished an arc in the anime, but that's not what I'm reviewing at the moment). The characters are basic cookie cutters of the usual stereotypical shonen roles. The hot headed hero, the new girl, the rival, and the master swordsman (Or in her case, swordswoman).
Either way, I look at it, especially after rereading RM and it becomes very clear that they're all basic copies. Another thing that bugs me is that they give you somewhat interesting villains, people that have flaws, that are actually after powerful and dark items and the fights are somewhat interesting, but they always end anticlimactically with some form of a Deus Ex Machina. I will not spoil anything for you, but it will always end with the main character gaining some amazing power, and basically beating down the villain and reducing them to just a miserable pile of bruises and broken teeth. It starts out good, builds up somewhat reasonably, then fails to deliver.
Crappy antagonists, terrible plotlines that never follow through, and the fanservice is so gratuitous that it's ridiculous. Good god, you cannot count how many times cleavage is severely exposed, or when some character has most of their clothes get blown away aside from just a scant few bits that barely keep her covered. I'm sorry, but in the end, I cannot keep reading this.
There are much better manga out there that can definitely fulfill your hunger for action.
If you enjoy Rave Master, or if you're bored, nothing is being updated, and there is absolutely nothing... and I mean NOTHING to do then read this. Heck, I suggest you read Naruto, Bleach, One Piece, Hellsing, or anything over this.
[/sigh] I should probably say something good about this...
If you like manga where the heroes always win, they never die nor do they ever really progress or develop further as people. If you like things to be the way they are and never develop, then this is the manga for you.
Otherwise, find something else, anything else.