This is answered well in snapcraft's official documentation.
In the interest of time, here is the pertinent portion:
Classic confinement is effectively un-confining the applications inside a snap. Applications which use classic confinement have the
same full system access as traditionally packaged applications.
Classic confinement is intended as a stop-gap measure to enable
developers to publish applications which need more access than the
current set of interfaces enable. Over time, as more interfaces are
developed, snap publishers can migrate away from classic confinement
Classically confined snaps must be reviewed by the snap store
reviewers team before they can be published in the stable channel.
Snaps which use classic confinement may be rejected if they don’t meet
Users should not attempt to override a strictly confined snap to make
it ‘classic’ as this undoes the confinement and interfaces defined by
the developer. In addition applications published as strict snaps may
misbehave when installed with the ‘–classic’ switch.
As for a recommendation, you'll need to weigh the risks in your own mind. Consider the publisher of the software, their reputation/recognition and the fact that classic confinement snaps are reviewed before being published. Classic confinement is not all that different than having done a traditional apt install in terms of the access it allows to the program.