first off, I've never cared for many of the so called dnd traditions so it's easier for me to like things that would horrify others, as long as they make sense story-wise.
fluff (I actually like a lot of the changes, but those could have been done without much effort in any edition):
- Feywild & Shadowfell, getting rid of the Great Wheel and racial pantheons, reshuffling devils & demons.
- “neutering” alignments (just discarding law & chaos would have been enough for me)
races:
- the elf /eladrin split and the tiefling’s mechanics (I hate the look, though)
- significant, active racial powers like FeyStep, InfernalWrath, 2ndChance (but
not racial bonus for allies)
classes:
- general stantardisation of classes, unified defence progression
- tiers replacing random prestige classes
- the idea of powers for everyone (but
not the mark system and per day/encounter martial powers)
- at will powers, rituals (potential like) for spellcasters (pity they did not drop “Vancian” altogether)
- multiclass "dips" sound good
- I hate power sources for spawning mongrels like the martial healer, but they do have the advantage of making the divine/arcane division somewhat less significant. They’re more like 2 schools among others now and every caster class doesn’t have to be lumped into either artificial cosmic category anymore.
combat:
- touch attack vs reflex (I wish they hadn’t dropped the ball on armor as damage reduction)
- bloodied condition could trigger many nice effects that make sense on both tactical and simulationist levels.
And random things like consolidated skills, fixed HPs, no more level drain.
As for the professed balance, faster or simpler gameplay, easier encounter design, extended sweet spot… they all sound good but I'm not sure I can take their word for it since we don’t seem to have the same notion of things like ”fun” or ”cool”
:\ I realise now that there are lots of “but”s even in things I like about 4e.