The sacred shield change is a huge blow to pvp, especially something like bgs where you are healing yourself. As previously mentioned, it's not so much the heal (although that heal is great), it's the almost guaranteed crit of your instant cast flash of light that will really hurt.

Having said that, I really think ret palys are still a little over the top in survivability. In my other life, my main is a mage. The amount of effort (or skill, if you prefer) required to perform well with that class compared to my paladin is significantly higher. Between SS, plate armor, cleanse and instant cast 4k heals, I can literally shut down classes like DKs or rogues (which is actually kind of fun for all the crap I've taken from them on my mage, but still). I can imagine how frustrating it is for them.

I do agree that the paladin class seems a little lost sometimes, and I wish they could balance it fairly well and just leave it alone. I guess it's a pretty hard one to get right.