Yes JD,even his classic Hothouse is not your average sf,more like fantasy really(science fantasy?) Its strange because i like Ballard too, the Drowned World was brilliant. Its not just space opera that floats my boat but the writing should be clear,something asimov strongly believed in.
Hmmm... I'd have said his
Hothouse was in company with such things as James Blish's "Surface Tension"; definitely sf because of the (at least moderately) scientific rationale for the tale, and the focus on long-range evolutionary effects; but I can see where the "feeling" of fantasy comes in, yes. And certainly, in one sense at least, he was dealing with mythic material. Which is also true, in its own way, in Non-Stop: he takes an old, familiar, sf trope (the generational ship), and explores it in almost mythic terms -- drawing a different sort of picture than Heinlein did with his "Universe" and "Commonsense", but at times closely related.
And actually, I'd have said Aldiss' writing is very clear, though adapted to his purpose. In something like
Barefoot in the Head, for instance, it reflects the changing interior reality of the characters and the world presented (hence the shifting techniques involved), while in
Report on Probability A it becomes almost painfully minimalist and narrowly-focused (the obsessive voice, it has been called) due to the ever-narrowing focus with its (paradoxically) ever-burgeoning possibilities of interpretation.
Aldiss is more "literary" than many harder sf writers, and sometimes a bit denser in texture (though Ballard, certainly, can be one of the densest writers around; he can also sometimes be one of the leanest), and I find this makes his books something one can revisit numerous times and the experience never be quite the same -- with his fiction, at least; his nonfiction much less so.
I'd be interested in hearing which of Aldiss' other works you've read, as well. Enjoying the discussion -- thanks for starting the thread!