You need to install the repository that contains the new version before it is available to the apt install command.
Run the command:
sudo add-apt-repository ppa:ubuntuhandbook1/darktable
Sudo apt update
Sudo apt install darktable
I haven't found any caveats in the new version. If you leave your old version the above will replace it with the new, so the first time you start DT after the upgrade you'll need to upgrade the DB - it's just an accept or deny choice. But the upgrade is mandatory to run the new version.
If you want to be able to go back to the older version, you should manually copy the ./config/darktable folder to a backup location, so you'll be able to restore the old DB after a downgrade.