I'm afraid I am not an avid fan of Constantine. He destroyed, once and for all, Rome's primacy, which ultimately led to the division of the Empire, and the eventual sack of Rome, which was allowed to happen by a weak emperor who had gotten used to the by then century-old idea that Rome was just another city in 'Romania'. His victory over Maxentius killed the Augustan system for good, and his reduction of the legions to a watchtower militia caused irrevocable damage whilst field armies, miles back from the frontiers, had a century - long free lunch at the expense of the dwindling cities. In the meantime, frontier areas became depopulated as limitaneii proved increasingly ineffective.
His re-invented mystery religion, now centralised and fixed in dogma, heralded a lack of religious tolerance which persists to this day, and assisted in a decline of literacy, rational thought and scientific enquiry which lasted, in the West, for a thousand years.