The first thing to notice is that the arena team standards can now be visible when you search for teams via the armory. Not only can you see who you came up against, but you can also see their fearsome (and sometimes comical) emblems. It's also nice to see that rating has been replaced by a relevance column. It seems to make more sense that way, and doesn't leave you wondering what you could possibly do to improve your rating.
My favorite new additions to the Armory site are the added categories. Now there are tabs dedicated to items, dungeons, bosses, and factions. In addition to the items tab there is now a feature that lets you search for an upgrade for your armor and weapons. This is a feature that I have been looking for on the database sites, and have only been able to find something close when I visit WoW-loot.com. Now I am able to see what Blizzard suggests as an upgrade to those darn Tempest's Touch gloves I have been sporting for so long. Yes they're good, but they're also boring!
There is a new concept added called the "Pin a Profile." This acts as a save button for the website, making comparison of profiles easy as pie. The basic stats of the pinned profile will be saved in the upper-right-hand corner of the page with some small navigation buttons around it for simple bouncing between pages.
Last but definitely not least is a filter added to the search called "Desired by." This search lets you navigate through the items database on the Armory site looking for items that are desired by your class. In this way you are able to select the uber delicious gear for your 70 lock or your 42 pally. I think of it as a small out of game version of the Auction House, only without the temptation to empty my gold purse.
Lots of yummy goodness out there on the Armory now. Let's hope the functionality will continue to improve and their server strength bolsters over the coming weeks. Otherwise the site traffic from the forums might make the Armory searching a little dicey.