Strange, isn't it, how people can differ in their response?
I think what I find difficult in Sibelius's Sixth is that I'm missing something - when the work starts there seems to me to be a lack of scale, I miss the sense that there is a vast world to be explored, a feeling I have in the Fourth, Fifth and Seventh (one of my absolute favourites), and also in Tapiola. It's this, I think, that has so far hindered me in my appreciation.
But, just to make clear that I'd rather love a work than leave it, I'll listen to it again (not now, but during the weekend).