Very viable, also good in other roles like healing a big group, healing fc, offensive healing. Fastest player on the field, can heal pretty good in move with rejuv/swiftmend, has great mobility because of the ability to remove ALL movement impairing effect once a second, can use stealth, armor provides around 40% damage reduction, 10% reduction from resilience if you decide to cap it aswell. You can get a great amount of HP in bear form aswell, up to around 3k with basic buffs if you roll a tauren and have BiS or close to Bis gear.
Cons are that you can't dps for ****, maybe some 250 starfires here and there, and moonfire combined with thorns cast on the FC (you or someone else) gets especially rogues to low hp pretty easily. I would consider roots combined with travel form very useful in O sometimes to catch FC easily and root him while rest of your O is coming to help ya.
Resto druid has kept me entertained 24/7 since I rolled it 3 months ago, versatile as **** and fun to play.
Yeah, armor increase in bear form went to 120% up from 60%, and stam increase in bear went from 10% to 20%.