Travelled on July and August 2021 from SWV to DR.
Both the times, it was comfortable trip and I coincidentally got same coach (B3 if I remember correctly). Even though it takes longer time from SWV to DR during monsoon (about 13 hours) I didn't feel any discomfort because the coach was well cleaned and perfumes were all over the coach. With rain, the experience amplified, plus this train stops at a lot of stations, so you can always explore the stations a bit and enjoy the smell of mud during the...
more... rainy season. In Ratnagiri, it can become a bit bothersome as a lot of people board here, but post Ratnagiri, you can go to Door and do some railfanning till Chiplun. I slept post Chiplun as it was tiring day. The first time, the train reached before time, but second time, unfortunately, the train got delayed by 3.5 hours due to some works between Chiplun and Veer. Either way, both trips were great experience.