I have been writing paper for journals for 46 years, and this is one of the best experiences I have had. The referees' comments were extremely useful and I received them within in one month of submission. After I made the revisions I felt my paper was much improved. The whole procedure was very efficient. The website was standard and easy to use, but when I messed up the submission of the revised paper (my fault entirely), I got help immediately that solved the problem.