Prince isn't too bad, but he can pull some Patchwerk level smack downs on a stupid tank.
It's an all around fight though, not just tanking. You need a good tank, you need good healers, you need good DPS and you need a raid in general that's smart enough to react to bad Infernal drops and other dicey situations.
As for Druid VS Warrior, the learning curve on Druid tanking and gear requirements are not nearly as steep. Although, any way you slice it the best tanking setup I found was a good Druid tank with a DPS Warrior keeping up Imp. Thunderclap. Druids don't remain *as* viable once you start the further raid content, but they're excellent for things like Karazhan.
If you're using a Warrior solely, just make sure he has smart gems and enchants and talents firstly. No 0/0/61 shit, no STR gems and enchants, etc. Have him keep up Imp. TC, Demo Shout and Shield Block the instant it cools down and you shouldn't have a problem with incoming damage provided he's decently geared.
Blow all of your cooldowns during stage 2. Heroism/Blood Lust, etc, burn him to the ground, because stage 2 sets the victory, if your healers can finish stage 2 with a solid ammount of mana, that's the key.
I've seen a lot of bullies about some of the Karazhan bosses and difficulty, blows my mind. A lot of the bosses in there you can easily equate to early Naxx bosses, easily, which is a fair jump for some of these small guilds.
I really don't understand where some of the snobs get off comparing them to ZG or even UBRS... I mean, UBRS? Are you ****ing kidding?