About 50% of the paper is writing (just as with Paper F5). I do stress this in our introductory lecture for F9.
You are not expected to write much, but you are expected to write sentences and not simply one or two word answers. Otherwise it is very much the same as with F8.
You should be practicing lots of past exam questions anyway, and reading the examiners answers to the written parts is useful (but appreciate that the examiners always write much more than they expect from students).