In my opinion, I think the series could use a change from Morrowind and Oblivion. The city music in Oblivion always felt too fanciful and giddy, and the outdoors music in both games was decent, but it was very static, and it had a weird ethereal, dreamy quality which seemed a little indulgent. It was as if the lushly rendered landscapes dazzled the composer so much to the point where he focused on the beauty of the game world over everything else. The music never changed when you got near an Oblivion gate or stepped into the wild and dangerous woods. Since Skyrim is set in a much more untamed land, I think it would even more fitting for the composer put some effort into giving certain areas a more ominous feel while still retaining a sense of beauty in others. The snowscapes of Skyrim may be pretty, but you never know if there's any Volkihar vampires or Ice wraiths hiding about.
Personally I wouldn't mind if ES5 took after the Gothic games in this respect. Kai Rosencrantz always did a good job of presenting a varied and dynamic soundtrack in the series. If you were walking over a hill with a nice view of the countryside below, the music might change to http://www.youtube.com/watch?v=DLyqSQhS6E0, only to change once again after you'd walked down the hill into the http://www.youtube.com/watch?v=wFlIR3t7HH0 below. I also think the style of Gothic's http://www.youtube.com/watch?v=RUODWSb-mk4 http://www.youtube.com/watch?v=dzXL9lycrh4&feature=related would also be a pretty good fit for the snowy solitude of Skyrim.
Anyway, just something I thought I'd share. What do you guys want Bethesda to do with the music this time round?