My problem with locums is that in many ways you only get the worst part of being a doctor, not the best.
The best parts of being a physician are the long term relationships you build with patients and other members of the healthcare team. You get to diagnose a problem, prescribe a treatment, and then followup with hopefully someone who is now feeling much better. When you are a temporary caregiver, you may drop in on parts of that cycle, but not see it completely through. It certainly can be a good option for some physicians, but for me it seemed highly unsatisfying. In addition, each place will have a separate EMR, hospital staff, resources, policies and procedures, and that can all be pretty disorienting/frustrating. Not to mention if you are procedurally based, you don't know the people you are working with and they don't know you and how you do your procedures (and because you are temporary by design, they are not incentivized to learn).
That said, there are many people who love doing locums and for whom it is highly rewarding and love the challenges and flexibility it provides. It just wasn't the right thing for me.