Finished Black Sigil and y'know, I can't really recommend it.
It was fun for a while, but battles just reach the point where they're mechanical (you know exactly what you should be doing) and they occur so damned often that it's just an endless grind (except without the normal benefits - leveling doesn't help much).
If you try to fight all the battles you run into, expect to emerge from dungeons bleeding, battered, and without any items - assuming you emerge at all. If you don't fight them, you'll be bored for a long time since battles run pretty slow (to the point where you run from battles slowly too!)
Love the graphical style, liked the characters (very Lunar-esque there) and the dozens of sidequests and hidden things were neat... it's just that the battles pull everything down.
Tierkreis was better overall. More epic story and (dare I say it?) more tolerable battles.