Forget Death Knights, I'm fairly convinced at this point that Druids are the true anti-Paladin. Now, as a disclaimer, I haven't gotten ye olde cow to 80 yet. It's also been a long time since I leveled my Paladin - but here's what I've seen so far.
Forget the difference in gear, as a Paladin you're always casting. AoE damage? Have fun catching up. Tank getting hit a ton? Keep spamming that FoL. You've got one on the move heal (once you can talent it), otherwise you're a freaking rock holding back the tide of damage. This is where the real heal face is born, grimacing as you will that HL to go off.
As a Druid, once my HoTs are out, all I can do is sit back and pray that Lifebloom 'blooms' before the tank dies. I love the diversity in spells available to me, and having a 6 sec CD AoE heal is a god send from a Paladin mind. I have to sit back and realize that yes - the tank is taking damage, but it's ticking back on him quickly from my four HoTs. Of course I don't know if I'm doing it right or not, I just toss up the HoTs and watch the party unfold.
At least I can run around with my arms in the air screaming when I get agro.
9/6/9 - the Paladin tanking mantra. There's a set rotation, and you deviate from it at your own risk. You're watching the raid for Hand usage (Protection, Salv, etc), and you've got two short CD taunts at your disposal.
As a bear I spam swipe. Now that I have mangle I might hit that, and in a high rage scenario I switch to my swipe/maul macro. /yawn. One taunt, plus FFF, and an AoE taunt with a long CD. Sure, I've got some nice CDs to use, but instead of my B-elf dancing self, I'm staring at a brown butt. At least I've got a charge.
I picked up ret again on my Pally, as I dork around looking for the right thing to do between now and Cataclysm. Since it's basically a 'hit the button when it lights up' spec, it's fairly straight forward. Granted, I'm no master of it yet, but I'm at least not embarrassing myself.
Kitty DPS though, hello timers. Now while leveling, it's pretty basic. Opener, bleed, combo point, finisher. I understand that at the end game however, it's pretty complicated. Keep up your roar, your bleeds, don't run out of combo points or energy, and stay behind the boss for your 'backstab'. It seems a lot more complicated than "Divine Storm for Justice".
I think this is one of the things that makes WoW so great. I can accomplish the same things, in an entirely different play style, depending on what I like. I can also understand the druid's lack of care regarding models. It's the same tree/bear that I've seen for thirty levels. Who cares what the armor looks like?
Once I get to 80 it'll be time to herd the priest through the LFD, finally rounding out my stable of healers. I may hold off on the priest until I can make a Goblin though. We'll have to see if I get a chance to play with them in Beta or not.