I managed to get Brigitte in PTR Quickplay a good handful of times. Her obvious weakness is immobility, so the maps and team comps in which she can be valuable for are limited.
That being said, she is great fun! She’s almost mandatory if the map favors Reinhardt. The mind game potential is actually insane. Brig can shield bash stun Rein out of shield so her own Rein can shatter. But if you do it with no (or late) follow up, the enemy Brig and shield bash you. Or worse, the enemy Brig could move past you and stun your Rein out of Earthshatter!