Well, the only written Icelandic I have ever seen was in the newspaper
my friends took. Since the pictures revealed what the story was about,
and since one had already read about whatever it was, it wasn't too hard
to follow the article. I don't know whether the number of words I could
figure out was 50% or considerably less, but knowing the subject makes a
huge difference. I can (sometimes) understand spoken Dutch too if I
listen for a while, but only if I have clues about what the subject of
the conversation. Swiss German is more difficult, but the same thing
applies.
Despite "doing" three months of Swedish when I was at the FU in Berlin,
I still find it very hard to get much from modern Scandinavian
languages, but of course I spent quite a bit of my time at university in
England and Germany being forced to read Althochdeutsch, which perhaps
makes Icelandic less impenetrable. In addition, I was forty years
younger when I knew the Icelanders and my brain was a bit more agile.
--
Robert Bannister