I put my thoughts in an article on Paladin Schmaladin. Here's the net-net.
In the end, I don't think this will have much effect on us. Some of us won't have 40k unbuffed HP anymore, but that's more an 'epeen' thing than anything else. Paladins have tanked successfully with the deck stacked far more against us than it is now, even with this small nerf. Generally, Tanks have not been the bottleneck to any of the fights so far. Maybe that will change in hard modes, but raids are wiping more to execution and learning errors, than class mechanics.
For me personally, Boston (my co-Tank) seems to prefer Blood so the buff will be very nice for him. It's not like we told him to lol go DPS when DKs got nerfed hard in whichever patch it was, maybe 3.1. I have every confidence I'll be tanking on Monday night. Well except for Dreamwalker who I've been lobbying to be Holy for because dropping huge Holy Light bombs on her sounds like fun.
Once the emotion wears off, we'll adapt. All Paladins really ask for from the Devs is to give us the tools to do our job, a short cooldown interrupt would be nice.
What all tanks want is the game to be balanced so that our raids don't have a worse chance of downing the boss just because we are Class: Foo instead instead of Class: Woo.