It's probably not too much of a spoiler to say that Sword Art Online is going through a big change after episode 14. Reflecting this, the series will be getting a new opening, "Innocence" by Aoi Eir (Fate/zero), and ending, "Overfly" by Haruna Luna.
For some spoilers...
The second story arc features the characters going into the online game Alfheim, which has flying fairy races and new skills system. The original light novels later introduce firearm and light saber battle game Gun Gale, then the more realistic UnderWorld.
Speaking of SAO, an early look at the Nendoroids
SAO Dengeki Bunko Autumn Festival goods and exhibitions