Alignment is one of those things that people have very strong and varied opinions on because their individual experiences with it have been equally varied and dramatic.
Spoiler for slightly off-topic discussion
People who have played in games where Alignment governed them (and not the other way around), and were restricted from play choices by their DM based on their alignment, or brow-beaten over the head with their alignment in the midst of their attempts at RP... or just plain blocked from a class choice by alignment... these are the players who are mostly in the "good riddance, I'm glad it's gone" pile.
Players who have had their alignment as a motivating factor, and not a controlling one tend to be in the group that disagree with the phasing out - because we lose its value as well as its limitations.
5e puts a lot more weight on the DM's shoulders, in MANY aspects of the game... and unfortunately, that's led to a lot of people claiming that the system itself is weaker, less powerful or more limited, when the reverse is true.... but whether that extra weight for the DM is viewed as a positive or a negative thing is easy to debate over. It's a system that encourages freedom and flexibility... but it does so by providing much more limited hard structure than older editions, which can lead to some DMs (and players) struggling at times, where a more rigid rule system might have supported them.
In terms of Alignment: It's not gone, and is still very much present and acknowledged both in mechanics and in universe... however, it has been moved to chapter 4 in the PHB - and is now covered and recorded in the section dealing with roleplay aesthetic and character, background and personality, rather than hard statistical features.
Alignment is a choice for many creatures in the D&D multiverse... many, but not all. It's still hard-coded into the multiverse in a very strong way. A devil that stops being evil, for example, is, by that very shift, no longer a devil - they literally and physically become something else if they truly give up their selfishness far enough.
For creatures that can choose, the idea that is presented is that it should be a roleplay tool first and foremost; a part of your kit as a player or DM but not the whole of it. Character choices inform alignment, which is flexible, and alignment informs character choices as well, in a two-way exchange between the player and their character, and then that character and the other entities in the world around them. A DM that tries to say "you can't" do something because of your alignment is doing it very, very wrong... and a DM who insists on flipping your alignment based on a single petty act is also misunderstanding the idea.
In video game terms, it's much harder to make alignment meaningful, precisely because it's appealing to the roleplay aspect and the aesthetic element of the game, not the mechanical... rather, you find that individual actions and choices have impact on your companions and those you have contact with, regardless of what your alignment reads as on a sheet of paper - though act certain ways enough and the bit of paper might begin to reflect your choices.
In most cases, the places where Alignment really comes up is when dealing with creatures that are stongly and inherantly somewhere on the axis - especially sentient items that will only permit certian types of people to use them - and beings that have an innate sense of where an individual's true heart drifts.
