There are two others (The Scar & Iron Council), though I'm not sure if you mean "more" in addition to them. I think he's moved on, though his other books are stylistically similar. Yeah, Perdido Street Station was pretty unrelenting, but I wouldn't have picked Yagharek's plight as the worst part.
To the original topic, I believe the first science fiction book I read was "Do Androids Dream of Electric Sheep?" What attracted it to me was not the story itself, which was unusal for me at the time and at present, but the ideas the book explored, which is normally a secondary interest.
The first fantasy book I read (that is, read myself) was certainly "The Hobbit". I was aged around seven, so I suspect parts of it went over my head. Then again, perhaps not; people tend to underestimate the perception of young children. In any case, it was a good book. It reminded me of a fairy tale, but interesting.
Luckily, I dodged the problem you described, Ari (that of being unable to reread my childhood favourites at a later age) as my parents seem to have conspired to put me in the way of good fiction throughout my young life; Tolkein, Pratchett, Douglas Adams etc. I daressay I read some pretty terrible stuff at school, but I didn't much care for any of it, so that was fine. I have had the problem of being dissapointed time and time again by the genre for being mostly rubbish, though.
Edited, Dec 14th 2008 9:35pm by Kavekk