Mmm, not much really changed, just a bunch of new content. The only major changes I'd say is that Tier 14 LFR now has improved drop rates so you can gear up faster for the tier 15 raid, and, all the world bosses are now tap to faction so you don't need to be in a group to have a chance at their loot as long as your faction has the tag.
The patch, though, was fairly massive. Here is a complete fast and dirty list of just about everything added:
-New isle, Isle of Thunder. Which contains:
-New Daily hub set up in stages, more dailies unlocks parts of the island. This is over on pretty much all servers by now, but, each stage had a solo story scenario you can still do so you can get the story without any of the work.
-New massive raid with 12 bosses + 1 hard mode only bonus boss.
-Weekly group boss quest that awards 150 valor for killing 3 summonable bosses on the isle
-Rare spawns that work like named quest mobs, anyone who attacks gets credit and a chance at their loot. Their loot includes 15 VP (100% drop chance, so effectively each rare spawn kill on the isle is an easy 15 vp), 1 ritual stone that is used to summon the bosses for the weekly, and, a key that is used for the treasure run
-That treasure run being a solo scenario that is more puzzle-y in nature than combat focused. Avoid as many enemies as you can, avoid traps, and do some light platforming to get as many treasure chests as you can in 5 minutes. The chests contain gold, rep items for the new daily rep, harmonies, Elder Charms (it is possible to get 20+ elder charms per week now, but, the new raid uses a different charm that replaced the Elder Charm quest), and keys that are used to unlock special chests at the end of the scenario that can have ilvl 502 epics from the new LFR tier in them.
-New world boss that unlocked with the last stage. His loot is Sha 2.0, drops 2 pieces of tier gear and a bunch of pvp stuff.
-A minor thing, but, worth mentioning I guess. You can find scrolls on the island that let you summon a Mogu ghost to fight. They drop treasure chests that usually contain even more gold, elder charms, and other various stuff like the chests in the treasure run.
-The rare spawns on the island also drop the quest item that begins Warlocks on their epic quest to get green fire. Doesn't concern you if you aren't a Warlock obviously.
-Outside of that they also introduced a second island called Isle of Giants. This island is straight up old school MMO grinding. There are Dinosaurs that are fairly challenging to solo except for the usual classes (hunters, blood DKs, etc.) which drop bones upon death. Get 999 of the bones and you can trade it for a special pet, 9999 of the bones gets you a white raptor mount that looks very similar to the original white raptor from Vanilla that was removed when the epic mounts were changed. Also every Dinosaur on the island has a chance to drop an egg that after 3 days hatches into 1 of 3 different colored raptor mounts (Black, Red, or Green). There is also another new world boss here who drops loot on par with loot from the normal mode of the newest raid tier.
-Daily fishing event that changes what zone it is in each day. This is mostly useful because the area where it occurs has massive amounts of 1 type of fish so you can stock up fast. There is also a boss you can fish up who generally drops an entire stack of fish, and, has a chance to drop the heirloom fishing book and the 3 rare fish you turn into Nat Pagle for his friendship rep.
-And lastly more pet battle stuff, bunch of new pets, new quest chain, and so on.
Oh also there's already a new patch on the PTR that will probably be out within a month or so.