Stanley Porter does a pretty good job of laying out the implications or tendencies for those who date Acts late and those who date Acts early. Porter notes,
"Each of these dates has implications for the portrait of Paul in Acts. The late date, promoted by Baur and his followers, explains the purported differences along three lines. First, the author could not have been an eyewitness of, or even close to, the events related. Second, the book was written after major events in the development of the early church had transpired and Paulinism had triumphed. Third, the work was written from a consciously apologetic and theological, but not distinctly historical, viewpoint. The earlier two dates provide for the possibility of first-hand witness of, or at least closeness to, the events. Those who subscribe to the early date tend to see close continuity between the Paul of Acts and of the letters. Those who hold to the middle date are divided: some disregard any connection between the narrative of Acts and what actually happened, while others contend for continuity."
Stanley E. Porter, "The Portrait of Paul in Acts," in The Blackwell Companion to Paul, ed. Stephen Westerholm (Oxford: Wiley-Blackwell, 2011), 126.