One of the things I do is take a look at staples that are in every edition and played a lot. In this case, I looked at the Sleep spell.
Most versions of the sleep spell effect Hit Dice of the creature. There is usually some scale of the number of creatures effected. This time around, 5th edition has taken the sleep spell and made it based on Hit Points.
My first reaction was neutral. I thought, okay, a little change up. But still a bit of a token one. But what I liked is the spell progressively gets more powerful with the mage. In past editions it was the big bomb spell at lower levels and discarded soon after. So the increase of hit points it effects as the character increases in level will make it a viable spell long term.
Since I'm on lunch break, I don't have any numbers. I'll check back when I get home and do some calculations to compare version.
So this staple of the game, for me, has been improved.