I am currently reviewing a book titled Forest of Lies for the British Fantasy Society, one of three I requested and received a few weeks ago. It's most interesting aspect is that it's self-published.
A year or two ago, I don't think this would have possible, in some places it still isn't, and it says a lot about self-publishing that it has occurred. The only reason I first noticed it is the publisher is listed as xlibris, a self-publisher based in the USA. The paper quality is also higher than a standard published book which is another indicator.
The cover design was also a bit of a clue as it lacked the picture sharpness of traditional books. That said, some professional cover designs are not much better, and some are a whole lot worse. The only advantage the professionals have is access to top quality software to process images and photos from professional photographers.
Aside from those things, none of which would stand out to an ordinary reader, there is nothing to distinguish it from a traditional book.
Well, there is one thing. Far fewer spelling mistakes.
I have recently reviewed Alastair Reynolds' latest novel, On The Steel Breeze, which had several spelling mistakes in it, a couple of which were really irritating and forced me to reread the passage to make sure my eyes hadn't gone funny.
None of this means the end of traditional publishing, but it does mark another step forward for self-publishing and can give all us self-publishers hope.