After having the chance to play a session of 5th edition, I am beginning to think that some of what I viewed as negative or optional might just be fine in the context of game play.
While I still think the healing to full hit-points after a full rest is too much, I can definitely see how the other healing methods work well to aid the flow of the game. In fact, the hit-dice mechanic makes for a good representation of fatigue, and other issues, when after a few days of hard adventuring a character could easily find healing up getting more and more difficult when fewer hit dice are returning after long rests.
The ability score increases still urk me, and until the Monster Manual and maybe the DM's Guide are in hand, I won't know if those can be removed or even need to be excised. In the Basic game, ability score bumps are all there are while in the PHB you can choose either a boost in abilities or a feat.
The magic system in 5e is a thing of beauty. Sure, I think the unlimited ammo combat cantrips are somewhat over-powered, and that meant boosting first level spells to a crazy level of damage production (Magic Missile does 3d4+3 damage, split into three 1d4+1 missiles), the flexible use of spells in higher spell slots is awesome. A wizard or other spell caster can take a low level spell and use a higher level slot to cast it making what would have been a minor spell into a more capable/powerful tool.
For example: The Command spell in the hands of a higher level caster is capable of affecting an entire adventuring party because in higher slots it affects more people instead of just a single target. Think of the party bursting into the lair of the evil high priest who simply Commands them to surrender. No longer does one person obey while the rest of the party eviscerates EHP, now they all might fall under the spell and be captured. No more interrupting a well prepared soliloquy, you pesky adventurers are going to have to listen to the grand standing of the big bad boss monster.
The Sleep spell likewise has become more useful. Sure, at lower level it can only do so much, but cast from higher level slots, and based on target hit points, it can be used against the big bad once the monster has been beat down a bit. Got a Paladin or other uber-goody in the party that wants to bring the villain to justice instead of just executing the miscreant on sight? Sleep is now your means of keeping intra-party politics calm.
There is one disappointment I have about the re-writing of spells. As someone that likes to use Enlarge-Reduce spells to break lintels so they crash down on enemies, the re-write rules that out by limiting the enlarge portion of the spell to only fit the area, not expand beyond. At least I can still use the Reduce portion to shrink a door out of its frame.
I've been a fan of the Advantage/Disadvantage mechanic since it was introduced in the first play-test packet. No more having to remember a host of fiddly modifiers. Simple and elegant, and it keeps things moving.
My next campaign is going to use 5e so that it gets a proper vetting from the DM side of the screen.