A friend already owns the first edition, is it worth it getting the second? What's new? what's changed? How's the balance with lower number of players?

All of these questions have been answered on this forum and others:

www.fantasyflightgames.com/edge_foros_discusion.asp

www.boardgamegeek.com/thread/832359/can-the-2nd-edition-be-played-similar-to-the-first

www.boardgamegeek.com/thread/716850/is-there-anything-completely-new-with-the-second-e

You can also check out the Rulebook:

www.fantasyflightgames.com/ffg_content/agot-bg-2nd-ed/support/VA65_AGoT2_Rulebook_web.pdf