What are the common pitfalls of SOA?

One of the most typical blunders is seeing SOA as a goal rather than a means to that goal. Developers that focus on developing an SOA solution rather than solving a specific business problem are more prone to generate complicated, unmanageable, and wasteful IT resource linkages. Another typical blunder is attempting to handle many problems at once rather than tackling them one at a time. Top-down approaches, which begin with large organization-wide infrastructure expenditures, frequently fail to provide benefits in a timely manner or to provide a compelling return on investment.

SOA is complexity. There is also ESB vs microservices styles. You have to pick correctly if going SOA, when do it, what kind of SOA, because it will be hard to undo that decision. So I suggest starting simple and going incrementally in one direction or another only when it becomes very clear that performance or other requirements demand for a distributed solution.