The program doesn't decode / encode the file during the process and that results in no quality loss. The process is very fast and pretty intuitive, so you'll have no problem when doing it.
One of the main avantages is that you can do batch changes. Load the files you want to merge and start the process. Mp3 Cutter Joiner will do it.
MP3 Cutter Joiner can be very useful and its simple but effective interface will be really helpful.
Trial version only edits 180 seconds per track.