Yea it's funny, though the climate suggests a large landmass I also can get what Feanaaro is saying and maybe it has to do with the scale you feel from the way things are laid out in terms of towns and cities. I guess it depends on whether you intend for the smallest settlements to be cities or villages. To me at largest I would guess it to be the size of Great Britain (including Ireland). I find scale a bit tricky myself.

I would strongly suggest you differentiate your rivers and your roads more! It is very hard to tell what is what despite the labelling.