Thin client PCs

We currently have two sattelite offices, soon to be 3 and then 6. for the past 2 years we have been successfully using terminal server to connect the satellite offices. With the number of offices multiplying, we would like to still use the terminal server as a solution. The problem we are having is justifying the cost of purchasing fully functional PCs. We are investigating the possibility of using “thin client” PCs. The solution seems feasible, however I would like to know if anyone has any experience using these types of machines and any pros and cons or just what to watch for.