I'm kind of torn in two over the whole e-book debate. On the one hand, e-publishing is easy and relatively cheap to do, meaning that any twopenny novelist can now put their work in the public domain and charge money for it. And consequently the online market is flooded with books of wildly varying standards, making it that much harder for the discerning reader to find a good book. Also, as a writer I personally would be embarrassed to have my ebook listed on amazon next to self-published vampire erotica - but that's just me :-P
On the other hand, if the manuscript is really well done and the author is willing to market themselves extensively, then self-publishing in ebook format might be more viable than sending your story to publisher after publisher.
Bottom line, I guess the overall success of the venture depends on many things.