Is Chinese writing pictorial, ideographic - or neither?
Is there is an accurate, brief characterisation of the language?


Considering it had developed over such a long period of time, it would be a trade-off between these two. The shortest, yet acceptable answer I can give is:

Written Chinese characters started with both pictorial and ideographic ones, but has grown more complex over history: Sometimes two characters that had the same sound would get confused and become the same character. Sometimes new characters are made combining the sound from one and meaning of another. Loanwords from sounds also exist throughout history. But the sounds also changed throughout history.