Recs.
Updated
SpecsUpdate
Pros
Pro Opera can have extensions from Opera Addons & Chrome Store websites
Opera supports cross-browser extensions. Opera Addons site keeps quality up compared to Chrome Store. Full of useful extensions, Opera also supports extra APIs like Speed Dial API, Extension Sidebar API and Stash API meaning wider variety of extension possibilities than in Chrome.
Cons
Con Publicly traded IPO
The Opera Browser is run by a publicly traded company (OPRA) in the US Stock Market, so in some sense they must be profitable, while not charging for the use of their browser; which generally means they're selling analytics data or personal information, which contradicts security and anonymity.
Con Proprietary
While Opera is currently available gratis (without monetary charge), it is currently not libre (meaning that it does not allow users to view the source code used to create, to modify that code, or to redistribute modifications) and is therefor neither free nor open-source software.