To be honest I don't have many impressions yet of the latest patch. I've only played for about two hours so there's probably a lot to be discovered.
I got to kill Ragnaros for my first time last night! You no longer need whatever item it was you previously needed from Hydraxxian waterlords to summon him. We cleared all of Molten Core on 6 raiders (two tanks, one healer and three DPS) and it was silly easy of course. It seems the reputation gains have been increased because I think I got 5-6k rep from one full run.
What else...I quite like the new animation and look on our Moonfire spell, did you notice it? If you've used Moonfire yet I'm sure you would.
Don't forget that you can clear out your bank a bit now as well if you still are clinging on to items like the Mallet of Zul'Farrak and other old stuff like that. They have either become gray items or been transformed to weapons now. I got 3-4 slots cleared up anyway.
I'll get to experience the Wild Growth cooldown in tonights Naxx run. I don't think it will bother me much though as I haven't relied on it as a main spell in any way.