Adobe just recently released three weights of their new Source Serif Pro to the public under the SIL Open Font License, and I couldn't be happier.
I am a self-avowed font nerd, and I'm super stoked to see that Adobe is continuing to add to their Source Pro family. Source Code Pro is the type that I use in my source code editors here in the newsroom and Source Sans Pro is the type that I use on my personal blog (that I also rarely update), so you could say I'm a big fan of the typeface.
It isn't flashy, but it certainly has the characteristics of some of the more venerable workhorse serifs of all time, including Charter, Utopia and the ever present Times New Roman. To my eye, it comes across as a cross-breed between Times and Charter (which was confirmed by the announcement on Adobe's Typekit blog.) The matching Italics are on the way, but I expect them to be excellent as well.
Source Serif Pro is free to download and distribute, and is available via their Github page here: http://adobe.github.io/source-serif-pro/