Second Tank

Disclaimer: My warrior is only 63, so we're not talking serious business here. We're not even talking heroics and Karazhan. But I have been tanking pretty often, so by now I think I have a decent feel for it.

It is not at all like tanking on a paladin.

Aggro:
Paladins throw aggro all over the place. In my experience it can be a bit tough to get it focused on one mob. But everywhere is equally and very mad at the paladin.
Warriors are much more focused. They do one mob at a time. Thunderclap will keep healing aggro, but DPS requires attention on each mob. The attention though, it is top-notch. Devastate puts out some solid aggro along with a great debuff, revenger is strong and super-cheap (2 rage). Then there's shield slam. Wow. I can't wait until I can get some block value gear.

Interaction:
Paladins feel almost like a strategy game: set up all the pieces in the right spot and then get rolling. It's a bit passive, but this has it's advantages, like making it easier to watch the surroundings and to eat while tanking. Keep up the cooldown rotation and it's all good.
Warriors are intense. Thunderclap and demo shout should be up. Sunders from devastate should be all over the place. Should I shield bash that caster? A shield slam would get rid of that buff. It really is a fight against the GCD because there's so much to do. Thankfully shield block is off the GCD and has a cooldown shorter than the duration, that gives breathing room, at least in terms of suddenly dying.

Stupidity:
Paladins don't have to worry a ton about stupid groups. Our aggro is everywhere so focus-fire failure isn't too bad. Our taunt is ranged and hits three mobs. Avenger's shield gives burst aggro on three targets from far away. DPS really has to try to ruin a pull.
Warriors don't have that. If you are dumb, you are very likely to die.

Oh Crap:
Paladins lack abilities to respond. We generally have hammer of justice, divine shield, and lay on hands. HoJ is useful on trash, no doubt, but untalented (and what prot paladin can afford the three points?) it has a longer cooldown than concussive blow. DS is a great debuff remover or maybe to buy a second for a heal, but in general it's a dangerous choice due to the short time as an invalid target, even with the on off macro.
Warriors, where to start? There's concussive blow on a shorted cooldown than HoJ. Last stand has paid off, though I must admit most often while soloing. It is like another health pot and a bigger health pool, temporarily, but it buys time. The cooldown isn't up every fight, but at only ten minutes it will probably be around when it is needed. Shield wall has a really long cooldown, but it makes a big difference when I do use it.

Preference:
I'm a little burnt-out on my paladin for now. The carrot on a stick of gear tires me. Maybe it's just my guild, but raiding seems to involve too much time and dying for too little reward. Gear isn't much of a solution since the gear would be for more raids. Unless I can somehow be motivated by the raids themselves, I doubt I'll be doing many soon. I still like the class, I just feel like I've run out of content that I enjoy.
My warrior is going through the same instances that I've done a hundred times before, but they feel much different. My shaman was DPS, my paladin was an AoE tank, now my warrior is a single-target tank. I don't feel like I need any gear I get, I don't care to chase it, but it's cool when it does drop. It's the same content, but it's a new experience. I'm still learning too, so that's keeps it all interesting.