Cons; Sometimes prevents the bolt locking to the rear on an empty mag - particularly on guns where bolt velocity is increased due to suppressor use, etc. . Also creates a situation where a shooter must be aware to keep his finger away from it during a reload so as to not send the bolt forward prematurely thus closing on an empty chamber.
It is also non standard so like ambi controls and whatnot if you have to pick up some else's rifle they very likely will not have a BAD lever and thus your skill set will not apply in terms of employing the bolt release.
Pro; it is easier to lock the bolt to the rear during a malfunction drill
Neutral; it is no faster or slower to do an open bolt reload with a BAD lever vs a standard bolt release
Hope this clears things up