Been doing the locums thing for about a year and half know while awaiting the start of a fellowship. Overall, I really like it and feel it's a great way to make connections and get in roads into a tight market. It's not for everyone and it takes a certain set of skills to be successful
Pluses - You're truely in control of your life. Work when you want, do what you want, don't do what you don't want. This is the biggest and most obvious plus to working as a locums and the major selling point. It's defiantly a nice feeling to tell your boss "Sorry I'm unavailable this month because I'm on vacation". You are not held hostage to one group or one hospital and you get to be above the politics. If things go south, you can leave at a moments notice and while others are scrambling to find a job you've got stuff already lined up.
Minuses - You do the stuff no one else wants to do and work when no one else wants to. As a locums, your bread and butter is providing coverage during vacations, weekends, and holidays. You don't have steady work so you need to be proactive about finding work
If this is the route you would like to choose, I would recommend being an independent contractor and not working with an agency unless you can't find work any other way. Scout out the area and make contact with as many local groups and ASCs as possible. Try to get in good w/at least 1 group that can provide you with somewhat steady work. Your goal as a locums is to make vacation coverage as seamless as possible, the more the surgeons trust you and nursing staff likes you the more valuable you are. You need to be very proactive about finding work, ask people about future vacations, request to take some weekend calls, contact other groups in the area, just make sure to book yourself out 2-3 months at a time to make sure you have a steady supply of work. Once you have 2-3 groups that trust you, you should have plenty of work to where you can start to be more selective about when and what you do. If you've got good skills and pleasent personality there will always be work for a good locums guy/gal