When I browsed the Steam reviews yesterday, most of the negative ones were about a new license agreement with onerous terms, and spyware. Those seem like good reasons for bad reviews, IMHO.
Edit: This comment provides a convenient summary…
It seems this [making the game free-to-keep this weekend] may be to cover up the bad news that Take Two/2K have changed their ToS to essentially allow all their games to be spyware. As the article says, it doesn’t look like the games have actually been updated yet, but that could just be coming
Also, even without updating the game files, it limits how you can use the game you purchased. You can be banned for using a VPN or playing he game on a VM and you risk being banned for using mods (it makes no allowance for mods in SP or private MP).