I find it obnoxious that Blizzard make you play through the entire first act on tutorial difficulty. In the (current) absence of competitive play, they should at least allow you to skip some of the initial mission in which you are invincible and you kill enemies 1-2 hits. They also restrict your ability use for this period of the game, which can make it rather boring (particularly for the Witch doctor I found).
I am ambivalent towards the new skill system. On one hand, once I level up a character type I'll never have to mess around in act one on normal again. On the other, I feel as if their dumbing it down for casual gamers (go back to farmville!). One of my friends had some valuable insight; Blizzard is attempting to have character customisability solely defined by equipment choice. I have no problem with this so long as there are multiple viable skill/equipment combinations.
The difficulty structure seems to be a bit droll for early play, but it does allow you to assemble a team for the high level play that will follow in later difficulties. The low level boredom can also be mitigated by playing as a barbarian, everything you touch explodes and the physics engine is quite gratifying