'Aesthetical Qualities' - a term to describe pleasing characteristics in texts?

A couple of points:

The German term is Exilliteratur, not exilliterature; if you want to anglicise it, you ought to render it as 'exile literature'. (See http://en.wikipedia.org/wiki/Exilliteratur).

Equally, there exist two similar words in English — (a)esthetic and (a)esthetical, the second of which is rather more restricted in scope (look up the words in the Onelook.com metadictionary to explore the differences in connotation).

Personally, I would use aesthetic qualities to refer to the stylistic characteristics of the texts under consideration. Literary features implies an emphasis on the individual technical devices used by the authors rather than on the totality of how they generate an emotional impact on their readers.

EDIT (see comment below)

As I'm sure you've noted, Onelook is not a dictionary per se, but a portal that leads to all the relevant hits/entries it finds in the set of actual online dictionaries that it knows about. So what you encounter will depend on which individual dictionary hits you click on. I'll restrict myself to Lookwayup.com's definitions of the adjective:

AESTHETIC
1. relating to or dealing with the subject of aesthetics ; "aesthetic values".
2. concerning or characterized by an appreciation of beauty or good taste ; "the aesthetic faculties"; "an aesthetic person"; "aesthetic feeling"; "the illustrations made the book an aesthetic success".
3. aesthetically pleasing ; "an artistic flower arrangement".

AESTHETICAL
concerning or characterized by an appreciation of beauty or good taste ; "the aesthetic faculties"; "an aesthetic person"; "aesthetic feeling"; "the illustrations made the book an aesthetic success".