Pros
No free professional editing, formatting, or cover art.
Fewer sales.
Less than 10% of the current book market.
Greater potential to publish crappy books.
Kontras
You have limited marketing resources (Often times you will have to do your own marketing and sales). There are plenty of guides online to aid you in marketing, but there is an abundance of information, sometimes with conflicting recommendations. Marketing can be overwhelming, but there are contractors or companies to hire for this exact purpose.