The Philippics were vital, so much so that as late as 33 (probably the year of the publication of his pamphlet, de sua ebrietate, "On His Own Drunkenness") Antony was still having to defend himself against Cicero's accusations. Plutarch's biography of Antony is obviously heavily based on the Philippics, and those speeches completely destroyed Antony's reputation. The whole purpose of the Philippics, delivered between September of 44 and April of 43, was to get Antony declared a public enemy, and in that it succeeded admirably. Cicero's opposition was key, since as soon as Cicero was removed following Mutina Antony's support began to return, though his reputation was forever tarnished. And of course it's due to Cicero and the Philippics that Octavian was granted an extraordinary command at Mutina in the first place. This is not necessarily to say that Antony might not have shot himself down anyway--the line he was walking, trying to appease both Caesarians and Republicans, was dangerously thin, and as in fact turned out the slightest disturbance caused the whole thing to come crashing down--but certainly the Philippics were vital in the way things actually played out