Considering Blizzard's more recent patch cycle, this is a fairly stuffed patch, with a big raid (so big that it splits into four LFRs on its own) and a solid amount of questing content. What more could I possibly want? Well, I'm glad you rhetorically asked.
New smaller group content
I'd really like some sort of five man out of all of this. I know we're getting scenarios, and those are great and all, but while I recently asked if we needed new five mans, that doesn't mean I don't personally want one. I like dungeons. We could have all sorts of dungeon content with this patch - a run into the Violet Hold to free captive Sunreavers/prevent Sunreaver captives from escaping, a battle with Zandalari skirmishers trying to make a place for themselves in Pandaria, plundering lost mogu secrets from their ancient tombs - and I'd be down for any and all of it.
More prehistoric creatures
I know, you're about to say "this patch is rife with prehistoric creatures, Matt" but hear me out. Almost all of the creatures we're getting are dinosaurs. Now, dinosaurs are awesome. But there are loads of alternatives we have yet to really get in World of Warcraft and I wanted to take a moment to give you a sense of what we're missing. There are dimetradon in game right now, which are clearly based on Dimetrodon, a synapsid pelycosaur. They're pretty cool and all, but now let me introduce you to your own distant relative (technically speaking Dimetrodon is also a distant cousin of ours) the Therapsidia. Therapsids are awesome, and technically, you're one of them. If not for the Permian end times extinction, therapsids might well have continued to rule the earth and we'd have never even seen dinosaurs evolve.
Not convinced? Let me show you a gorgonopsid in action. Inostrancevia, my favorite of the gorgonopsids, was a massive and terrifying sabre toothed predator nearly four meters long, and that's just the actual animal. Now just imagine what you could do with that thing in game. Also keep in mind that as mammal cousins, these things could very well have hunted in packs.
There are plenty of other prehistoric creatures - Indricotheres, Andrewsarchus, Hyaenodon - from the much later Cenozoic as well. In fact, there's really not enough room in this post for all the prehistoric creatures I'd recommend adding to the Isle of Giants, if given my druthers.
More void storage
I'm seriously never going to stop saying I want to see more of this in every patch.
More story progression quests
These are likely there, just not accessible yet, but one of the things I absolutely loved about the Dominance Offensive/Operation: Shieldwall questing, the way as you unlocked reputation new quests would appear (not daily quests, one time quests) that gave you a sense of a progressing storyline. Even better, these quests ultimately lead right into patch 5.2, and I want dearly for patch 5.2 to pay it forward into 5.3 with similar awesome story progression.
Mostly, though, I just want Inostrancevia in game. Look at that guy! Tell me he wouldn't be the best mount ever. I would never ride anything else.
Mists of Pandaria is here! The level cap has been raised to 90, many players have returned to Azeroth, and pet battles are taking the world by storm. Keep an eye out for all of the latest news, and check out our comprehensive guide to Mists of Pandaria for everything you'll ever need to know.