Kobolds and Catacombs is the new Hearthstone set that was released today. So far it looks pretty good (although every new set tends to be good on the first day just by virtue of being new). It has a free single player adventure which is fun. You face progressively harder AI opponents and get to add cards to your deck after each win. The higher levels are actually pretty challenging. On my first run I got to the 6th opponent (of 8). If you are interested in watching I have some of my YouTube videos below. I also made an all spells Hunter deck (although missing a couple of key cards) to try out the new Hunter Legendary weapon.
Dungeon Run Adventure Attempt 1 with Mage
Badly made Rhok'delar Weapon Hunter Spells Deck
Kobolds and Catacombs Pack Opening