One thing every student learns when studying the book of Acts is that the author didn't intend for it to be a blow-by-blow account of the early church. At times events are overlooked, rearranged and perhaps even presented with a particular agenda.
When I introduce some case studies on how the author of Acts used history to write Acts, they begin to realize that the ancients wrote, understood and used history very differently than we do. At the same time, there is little doubt that there is a strong historical core supporting the book's outline.
Craig Keener has just published his first installment of what will be a four volume set Acts: An Exegetical Commentary (Baker Academic, 2012). Asbury seminary has posted an interview with Keener in which he explains why he argues for the essential historicity of Acts. It is a good overview on how the ancients used and wrote history.