Yes, I have just read two biographies of Constantine very close together. It actually works, both books have a certain focus. And with the reliability or paucity of the source material, there are different interpretations to be set out.
Like David Potter’s book, Stephenson also takes some time to set the scene. For Potter that was the administrative and imperial state before and after Diocletian. For Stephenson, it is the religious state of the Roman empire in the late third century. Where Potter was happy to sideline the topic of religion, Stephenson wants to set out his views on Constantine’s conversion: a real conversion but due to his identification of the Christian God as a pagan style victory giving god. This is contrasted with early Christian pacifism and an army that was among the slower parts of society. While Potter was sharp and analytical, Stephenson (although clearly knowledgeable) doesn’t build his arguments quite as tightly – they sometimes seem a bit speculative.
The book doesn’t just focus on religious issues. The military and governmental sides are also covered, making the book perhaps more rounded that Potter’s. One interesting discussion looks at Constantine’s development of Rome and Constantinople. After looking at how Constantine adapted the work of his rival Maxentius in Rome, he suggests that another rival Licinius started work on Constantinople before having his contribution more successfully removed from history. Both authors do see a similar motivation in refounding the city, as Potter described the previous use of Nicomedia as an administrative centre. Ultimately the emperor was looking for a fresh start in his own image.
As a character both pictures of Constantine feels similar in many ways: determined, ruthless but often tolerant and morally led in decision making. Despite twisting religion to suit his own views and ends Paul Stephenson’s Constantine feels less cynical than David Potter’s. Stephenson does though point out the bias of our biographical sources – usually religious – and suggests that our image would change if we had accounts from other backgrounds. This is probably the best introduction to the emperor that I have read (actually, I’d suggest Mike Duncan’s podcast), but it’s not without its odd twists and nuances – particularly some of the speculation. Personally I preferred Potter for the better defined scope and analysis.