Bear is my alt. So take the following as you will. Everyone here seems to be pretty rosy, so I figured I’d point out some of the less than stellar aspects of Bear.
One of the worst parts of Bear is your relationship to Dodge. Reforging all your gear to a stat that doesn't come naturally is counter-intuitive. Nowhere in game is this relationship apparent. You have to do outside research to figure it out. This bugs me. It's as though Strength made Holy Priest's heals larger and worked out to be their best stat. Hell, let’s face it. NOTHING on Bear gear screams “tank”. It’s not like Agi paints the picture of strong damage absorbtion and the whole "Hit/Expertise are worthless 15 seconds into the fight" is not something a lot of Tanks are comfortable with or even understand.
AoE threat with trigger happy DPS (which, let's face it, most of them are) can be rough. Many DPS do not understand how Bear AoE threat works. They just assume everyone’s a Pally that gradually builds up AoE threat as opposed to the burst and flatline truth. You’ll Swipe and then Thrash and DPS will go hog wild in the 3-4 seconds before your AoE is off CD again – forcing you to taunt/single target the mobs they’re peeling off you which leaves you less GCDs for further Swipes and Thrashes leading to more peeled mobs. With Swipe changing to a 3 second CD, things should get easier.
Assuming you want to raid 10s or 25s, you will need to amass a LOT of gear. You will need to intimately understand your different options and swap multiple pieces of gear before every boss. Trinkets are especially important and can make swift and large changes to your set up rather quickly. However, you will still need to have sets with different gemming, enchanting and reforging priorities. You can sometimes get away with a “base” set for farm content, but expect to change much of your gear and even your spec to suit each progression boss. Learn to love the wardrobe. And even then, don’t beat yourself up too hard when you go to pop your TB trinket only to find you’re rocking double Stam.
As with any Tank, there’s a lot of pressure. You can be solely responsibility for the failure of any given encounter. If you’re not good at what you do, even the best DPS and Healers in the world aren’t going to be able to save you. On the converse side though, if you are pro enough, you can carry even mediocre groups to victory.
All that said, Bear is pretty fun. Personally, I love it. Druid is just an amazing class and tanking is a great challenge. It’s nerdy to say but there’s much more thrill in charging in and going toe to toe with a boss than there is in standing in the back waving your hands around or even sliding behind the boss and whacking him with a weapon.