My Shepherd is smart, loving, and loyal. He's also mean as a snake when it comes to strangers. Great dog for keeping my truck safe in the snow park!
The Lab in them could mellow them out and be a totally awesome well rounded dog. A pure Shepherd is amazing with kids in it's own pack, but I wouldn't trust them for a second when friends come over and play. The protective instinct is great, but could be a liability in the wrong situation.
See how the parents are if you can. That should give you an indication of what you're getting into.
before:
after: