Almost seriously =))
All changes since patch 4.01 make me very happy. The game is rapidly changing from just "very-very cool" to "ultra-awesome".
(this thread is gonna be full of incoherent, exalted rambling and praising of blizzard entertainment. you've been warned)
For instance:
1) New trimmed and awesome talent trees;
2) Specialization selection, adding flavour to each specialization
3) New UI elements for classes (Eclipse, Holy Power)
4) New finer textures and models.
5) More flight paths!
6) Awesome changes to Old World - in physical sense - all those cracks, disasters and advancements
7) All-out war between the Horde and the Alliance, with renewed strength and hatred. Isn't that awesome?
8) Quests. This change is just godlike. Questlines are interesting now, even exciting. Quests base around hubs, no more need to run to earth's end - everything's close enough to be convenient, yet not to be trivial. Questlines are well thought-through and incorporate a lot of new mechanics. That quest giving/handing w/o need of NPCs is awesome too.
9) Dragon-punching (and tossing) in Badlands and
10) A lot of renewed, rewritten or continued storylines
11) Phasing. It makes things feel much more real than before.
12) Epic questlines. At first I though I was lucky to stumble upon the zones with such, after several in a row I understood that most zones gonna have such...
13) A lot of Demon Hunter lore/presence. Before they seemed strangely absent in Old World. Won't disclose details, in case people don't want spoilers.
14) A lot of attention to major lore characters - Malfurion, etc.
15) PvP changes - Rated BGs to those who like happy zerg-rushing (yes-yes, that may not be the best tactic in a rated bg, but still) and don't like Arenas, new BG brackets for alts, etc.
16) Archaeology! Sheer awesomness!
17) Worgen! I love just about every aspect of them.
18) Goblins! Normally I don't like midgets, technology and too much humour in the game, but goblins seem to combine all these negative (for me) features in quite a positive cocktail.
19) Wonderful new zones - all of them. Incredible design and execution.
20) New dungeons - just breathtaking.
phew... my fingers hurt typing =)
So, do you like Cataclysm and pre-Catalysm changes? Are you happy as I am? Do you have anything to add to this list of awesomness?