Volume one of Tokyo Ghoul was a so-so experience (still a solid three) for me, mainly because I had difficulty understanding/relating to the motives of a few of the characters - Touka, for example. She's horrible. 
 I don't care much for either insta-love or insta-hate ("strong dislike") or any other more powerful emotion without a plausible base upon which it is founded. In Touka's case, I don't understand why she would feel so strongly against Kaneki as she does. [What one would consider a plausible reason is of course subjective, however I would've been glad for even a vaguely hinted at "explanation" from Touka. My friend, whose favorite manga this is, did suggest one such explanation, one I could even understand, but I don't feel that the book offered the same.] 
 The same goes for both Renji and Nishiki. 
 The story is promising and I like the other characters, especially Kaneki, of course, Uta, Yoshimura and Hinami (I really like that they've got a fairly wide age span between characters) and I'm sure that there are a lot of exciting potential relationships between the characters.