That standard Cerberus's main weakness is relatively thin armor compared to other mechs that big. All 'mech design is based on the principle of Firepower, Armor, Speed, pick two. While most assaults take firepower and armor, the Cerberus chose speed instead of armor, resulting in something that can easily keep up with heavy 'mech formations while delivering assault-grade firepower, but cannot take the same kind of firepower in return. If you can give it good escorts, keep it at long range, or use the firepower overwhelmingly to quickly kill your enemies, this can be a very good 'mech for you. However, if you plan to slug it out against other assaults or otherwise get in the thick of things, you might be advised to take something more durable.
One variant does address the armor by replacing one of the Gauss Rifles for an ER PPC, as well as additional pulse lasers, using the saved mass for armor and heat sinks. This version lacks the crushing long-range firepower of a dual Gauss design, but makes up for it with serious close-in punch, as well as the armor to stand up to those Gauss-toters long enough to close and use those pulse lasers.
