The Sleep spell caught my attention -- twice.
On the first read: Ok, I will most likely be a infrequent player/GM for D&D going forward (my group has moved on overall). So I am looking at this version to see if they alleviated some of the things the our group came to dislike with 3rd and 4th (what little we played). So I wander through the PDF I am really digging what they have done. They really cut down on the "fiddly" of the prior editions. I presume the monsters are retaining some of their 4e "lets make the system usable for the GM" focus as well. Overall, I am getting excited by this new version.
That is until I hit the Sleep spell. Its like they took all the fiddly and stuffed it into that spell - roll 5d8 and start subtracting current HPs of the critters. If cast right at the start of the fight it might not be bad (ok, you rolled 20, and each goblin has 4 HPs, so 5 go down). But ugh, messy if cast in the fight after some HPs have come off the totals.
But then thinking on it and reading it again this morning: Was Sleep written this way in the playtest? This spell is much more powerful than pre-4e (I did not play enough 4e to know how good it is). As long as a critter is not immune to Charm you just beat on it until it has around 20-30 HPs and Sleep it. No save. I did not see a Coup de Gras rule in the Basic, but even if the DM is strick that still means everyone can gather round and get a free attack on a prone sleeping creature. Kinda feels like an anticlimatic finisher for the BBEG. If I am understanding the magic rules, the Wizard could then just Sleep the beast again if it somehow still has HPs after the first attempt to finish it off (and they have an open slot).
(lets be honest with ourselves - one of the players will know the relative HP level of some of the big bad critters - I guess Giants will need their own Bag or Rats so the sleep spell knocks them out first

).
In the end, this might be OK as it keeps the Sleep relevant even at high levels. As a DM it would be fun to Sleep a high level party that is on the edge of a TPK and finish them off with a Sleep spell.
But otherwise 5e looks like a lean, mean system!