If you're playing solo you might not be missing out on much aside from it is a really OP mech (almost every weapon is viable with it). If you play with teams, Panther strength is even more exaggerated because players, unlike mindless bots, know to hide behind your shield. 2 panthers side by side are quite difficult to kill indeed unless you dash in (reckless) or have helix/rocket mortars. Smart panther play is certainly one of the most useful in the game.

All that being said (Panther is my favorite mech); I wouldn't recommend buying it if you already have a very great hangar without it. This game is not really worth spending $$ on currently. Most players that have this mech got for free/cheap prior to the worsening updates.