I have found Geza Vermes' other books thorough and helpful in pinning down as well as one can who Jesus really was and what he actually said, as opposed to what was said about him or ascribed to him by editors.
In The Resurrection also, Vermes applies his forensic eye to the witnesses, reports and emerging stories pertinent to the "event" by which Christians define themselves. However, he doesn't go directly to the matter of "did he or didn't he?" and whether the witnesses were credible. Rather, much of the book is taken up with a review of the understanding of "resurrection" in the minds of the Jewish people from patriarchal times, through the second temple period and on to the New Testament record and discussion.
That is all very informative and important contextual information for assessing the congruence or otherwise of the unique individual resurrection that Jesus is said to have experienced and exhibited (subsequent to the "event" itself).
Vermes' exposition and analysis of the synoptics' record, the Johannine presentation and Paul's interpretation is thorough. However, the hoped-for climax ("did he or didn't he?") turns out to be a whimper.
Having discarded various possible explanations for what actually happened or was believed to have happened, Vermes can only conclude that the reports of Jesus' rising were so stimulating, so consoling to his depressed followers, that they were galvanized to the extent that their initial demoralization and cowardice (the males', anyway) was replaced by the kind of triumphalism and millennialism reported in the Gospels, Acts and the writings of Paul. A complete turnaround, in fact, that Vermes can't really account for and which left this reader feeling, if not a little cheated, at least a bit disappointed. Surely Vermes doesn't believe that an upsurge in enthusiasm, of itself, is going to lead to the heroism and self-sacrifice of the apostles and Paul and the sub-apostolic martyrs, who would have heard the stories from early believers. In consequence, one can understand the position of those Christians who argue that something quite extraordinary must have happened to launch the passionate missionary efforts of the apostles and lead them to martyrdom as a result, particularly in view of Vermes' inability to come up with any plausible reason why no one came up with a body. Had the apostles simply got excited about something that never actually happened, it would have been simple enough to disabuse them by showing them where Jesus' body was lain. Vermes can only suggest that perhaps the women went to the wrong tomb, or the body had been relocated (it was someone else's tomb, after all).
It's also worth noting that Vermes makes an early (page 1) disavowal of the theory that Jesus did not actually exist, asserting that the problems arising from the "Jesus Myth" thesis outweigh the solutions it proposes. However, in regard to the Resurrection, perhaps the Jesus as myth theory may be an attractive one.
As an alternative to the traditional and evangelical explanation of early Christian messianism rooted in the literal event of Christ's resurrection from the dead, perhaps we can take a more radical view of the kind of deconstruction Vermes himself has undertaken of the New Testament records. After all, though we know that Christianity was a charismatic force, drawing considerable support among the dispossessed and relatively powerless elements of the population of the Greco-Roman world we have limited evidence of how this came about. The Gospels and Acts were written decades after the events they speak of and it is clear that Paul's message, though it became normative, was idiosyncratic. We also know that the growth of the church was very slow for the first hundred years or so (R. Stark 7,530 souls in CE 100), but it appears greater and more dramatic because we view it from our perspective in history. Maybe the early post-resurrection enthusiasm and its missionary outcomes were not really as they are presented in the scriptures.
Vermes is 84 years old now, and, to my knowledge, not extended his of early Christianity beyond the fall of Jerusalem in CE 70; however, having set the ball rolling with his deconstruction of traditional Christian perspectives on the life and times of Jesus and his immediate followers, it would be interesting to see what he might say, had he the energy, about the emergence and spread of Christianity following the resurrection, from Jerusalem to Antioch, to the Pauline missions and the time of the sub-apostolic martyrs, especially Ignatius and Polycarp and their legacy. There is plenty written about the early church, but it would be interesting to see Vermes' take on it.