Sonic Origins is one of those few cases where I wish an option between positive and negative would be a thing for Steam reviews, however the negative backlash and certain tweets from developers explaining their situation on the game being a rushed job, as well as playing it for a few days now, put me into a mood where I just had to write down my complains and worries in a small review.

I've been dying to play the Christian Whitehead's Retro Engine remasters in an official way on PC for almost a decade now and while the new animated cutscenes add more flavor to each individual game got me crying inside, as well as new QoL improvements being something that people new to the series will appreciate, the core gameplay shows some rough edges such as:
Tails AI not respawning in Sonic 1 and 2.
Collission issues throughout all games, especially Sonic 3. Sonic CD having the least issues.
Sonic 1 and 2 having a jump roll lock, making the games harder than they should be.
Sega apparently not caring or didn't bother getting the licensing for the original 1994 Sonic3 OST.
Sonic 3's physics being totally different compared to the other remasters and original genesis game.
Sonic CD lacks Knuckles as playable character.
Sonic CD missing some sound effects compared to the 2011 rerelease.
You can't replay a completed save, if you wanted to go back and collect all the Emeralds in 1, CD or 2.
Audio mixing is all over the place.
Denuvo DRM will force the user to have an online connection to play the game once in a while, despite it being singleplayer.
And much more.

It's more so concerning that they delisted the original genesis games on Steam and on other console platforms, forcing people to buy Origins. While all these games play good, they are far from perfect and sadly I don't think it's worth the $40 price tag at the moment. Again by no means is Origins a bad game but it's lacking polish.

For now I recommend playing the fan decomps for Sonic 1 and 2 and wait for a sale. You might also want to play Origins with mods to enhance the experience and fix some of the issues that came with the game by default. It's still unclear if Sega is gonna support the game in the long run, fix leftovers or will just run away with everyones money.

Tweetchain from developer Stealth aka Headcannon on Origins:
https://twitter.com/HCStealth/status/1540161919851540480
Video from youtube user "bickuribox12", who summarizes all the issues and complains probably better than this review in better length and detail:
https://www.youtube.com/watch?v=z7NUzlg5kIE