I own it.
You're right but don't forget, this also includes Sonic and Knuckles, and in the game they bundle it with Sonic 3, effectively calling it Sonic 3 and Knuckles, just like when you put the cartridges together growing up with a Genesis.
I have played the game, experienced numerous bugs playing it, HOWEVER, there are some improvements to the original games. The biggest improvement to me is the fact that you can't lose - there are unlimited lives - and when you achieve things like 100 rings instead of getting an extra life you get coins. Coins can be used for two purposes - to unlock media in the game, or to retry special stages in all five games.
I was playing Sonic 2 and there were just two parts I kept dying in. If I didn't have the unlimited lives I would have to restart from the beginning - and most of my deaths happened at the very end of the game. Also, on a smaller side-note, the spin dash is now in Sonic 1, and definitely makes it more bearable to play.
I would also note that this game is for virtually every system. Steam/PC, Switch, X-Box and PlayStation. The $40/$45 price tag is a bit high, and they weren't able to secure the rights to Carnival Night, Ice Cap or Launch Base Zones music, so they updated the prototype music - which in my opinion sounds worse than the original beta music.
The rumor spreading around is because they refused to put Michael Jackson in the music credits they had to pull them - however - MJ himself distanced himself from the project after finding out about the poor quality of music associated with the typical MIDI file anyways. I don't fully understand it, however, if you own the Steam/PC version there is a mod already out to replace the remastered betas with MJ's tracks.
I must remind you however, that this game is entirely hand-crafted from the originals - not direct ports from emulators or simply remasters. There was a lot of work put done into this, which actually probably justifies the cost of it. While Sonic Mania was $20/$25 and it would have been nice if Origins was the same price, you are essentially getting five games in one, whereas Sonic Mania is just one lengthy campaign.
I haven't played the whole thing yet, but I'd rate this game and what I've done so far a B- on the academic rating scale. If you enjoy classic Sonic just get it now. Any bugs you experience will probably be patched up later. If you don't know if you should get the PC or console version, I would recommend the PC version so you can fix the music issue you'll experience later.