General:
I like the new dice. d4 is just brutal for Wizards/Sorcerers, and I always kinda thought that rogues and bards could use a bit more resilience, too.
Starting HP:
Beyond the standard deal, I like the The Constitution variant, where you get the con score at first level.
Actually, I'd give them the con score and mod at first level, to make it more consistent.
Cleric:
The favoured weapon proficiency is a nice touch.
The Orisons are a very good idea (same goes for cantrips), and so are the domain powers - though I haven't looked at them too closely yet.
The only caveat is the lack of generalist clerics that don't have to worship a deity. .
Fighter:
Another good one, and since they're getting something every level, they're both more powerful and more interesting than before.
I guess those new abilities replace weapon specialization and the like.
Rogue:
The new talents look interesting, and the fact that sneak attacknow works without a dozen extra feats and abilities and so on.
By the way: I wonder whether crits work the same way: against almost everything.
One thing I'd like to see changed: Trapfinding. I never liked how only the rogue is the only (in the core rules) that can use search to find traps. A skill is a skill.
I usually make the 3.5 function of trapfinding generally available, and give rogues something similar to elves secret-door-finding, so they get to make a search check automatically, as if they were looking actively.
Wizards:
Looks good so far. Cantrips and School powers seem a good idea, and I like how specialist wizards are handled.
The "item familiar" is another good idea. Those rings don't mind if you don't remember them for months on end.