Protection kills faster now as well (we actually get some STRENGTH on our gear... YAY!) and Prot is not as dependent on spellpower gear now since you get a Stamina to Spellpower conversion through talents (1000 Stam = 300 spellpower) so it is now feasible to use warrior tanking weapons and gear and still hold threat just fine.
Before you hit level 60, you can almost spec any way you want to and be just fine 95% of the time. After 60 your spec starts to make a BIG difference, but Prot can actually pump out some decent damage now, as well as being a THREAT MACHINE!
Basically what it boils down to is what do you like to do?
Holy can heal like crazy, and can put out VERY respectable DPS now so is viable to level with.
Prot puts out better damage than before and has virtually 0 mana issues anymore... still a bit slower to solo/level with, but can grind 5-10 mobs at a time, thus making the "kill x mob" or "get x number of drop y from mob" quests really easy. Also just superb in instances, even better than before!
Ret is now a killing machine with 0 mana issues and some fantastic healing ability.
Overall, all 3 trees got MUCH better with this patch, so it is mostly what you like best now. And, as I said in my previous post, there is no reason not to have several different pieces (or sets) of equipment and respec whenever you want or need to.
I happen to LOVE being a tank, so that is what I am staying for the most part, but some weekend I am going to spec Ret and throw on my "crappy" Ret greens and blues and just go have some fun with it.