Since German literature and I don't really get along, I'm not qualified to judge this criticism. But my guess is that the target of Greiner's attack is not unlike the kind of nerve-rackingly banal "and then, and then, and then" novels that have been popular in the Anglophone literatures for a while (and upon which I have already heaped a fair amount of scorn), and I think I know enough about this literature to make informed comments.
You know - the simplistic quasi-fiction recounting the meaningless lives of dull and dreary protagonists, typically involving little more than detailed descriptions of facial blemishes, bowel movements and the making of jam and marg sandwiches/fish fingers (while in the ashtray a lonely cigarette smoulders towards oblivion). Dogme 95 in print (only not quite as good). The New Puritans (and who remembers them?).
Agreed, agreed - much of this stuff is awful. However, I'm just not so sure that books carrying their (or their authors') "doubts about language" (Sprachzweifel) on their sleeves are necessarily "better", which is what Greiner seems to suggest (and a very "German" idea this is: I have heard very similar statements from various colleagues in my institution) . The "Look: All language!" novel has become something of a bore. As has the underlying notion of the linguistic construction of identity. As though there weren't other relevant aspects of identity-shaping experience one could be sceptical of or reflect upon in literature:
What do I understand? Now? About anything? Even the simplest things in front of my eyes? What do I understand about the geraniums in that tub?
Only that they're geraniums in a tub. About the biological, chemical, and molecular processes that lie behind that flaunting scarlet, or even the commercial and economic arrangements that create the market in bedding plants, or the sociological, psychological and aesthetic explanations for the planting out of geraniums in general and these geraniums in particular, I understand more or less nothing.
I don't need to. I simply glance in that direction and at once I've got the general story: geraniums in a tub.
I'm not sure, now the question's been raised, if I really understand even what it means to understand something (Michael Frayn, Spies 138).