I love it. A very good use of The Black Hack. I never got a chance to play Planescape but have read through some of the books and recognized a lot of potential in it.
1.) There are a few typos and formatting errors. Nothing glaring, but there are a few things you could tweak.
2..) I really, really love what you did with the character background generation and the addition of the Adventurer as a class. Please consider expanding the document with additional colorful backgrounds as time goes on. I think you might suggest somewhere that not all characters will be "human", I think it's in-between the lines but you might want to state it clearly (even just as an official suggestion from the writer). You might take the racial aspect one step further by pulling some ideas from The Lamentations Of The Space Princess SRD. I thought the way they handled race in that was very creative and quite in the spirit of OSR DIY gaming.
3.) As an illustrator/artsy type I found it a bit sparse (I know that is common in TBH games but...). I wish there had been at least some sort of map of the multiverse and perhaps a more emotive cover more in line with the other TBH products. Maybe something black and white with funky glyphs on monoliths overlooking an alien vista... but that might be too grimdark. If you're looking for some interior art, please check out my stuff here on OBS. :^)
Seriously a great game though. I can't wait to run it for my friends who haven't yet accepted the greatness of the TBH system.