I am in the process of self-publishing my first novel. I am getting a limited number of printed copies done, and am also looking into e-publishing.

I am wondering if it is really worth investigating platforms other than Kindle and Amazon. It seems that they have such a huge share of the market, I already have a Kindle version up and have had a few sales. I am working on the iBooks version now, but am even having second thoughts about that. I have heard about Nook and Kobo, but don't know much about them. As for Nook, it seems Barnes and Noble are pulling away from e-publishing at the moment..... Do other e-book retailers offer something that Kindle doesn't?

Any advice would be appreciated....