S30 came years after S40 and only targeted low-end. S40 was a rather well-received UI, but neither it nor S30 were ever used on smartphones. The only UI used wi

S30 came years after S40 and only targeted low-end. S40 was a rather well-received UI, but neither it nor S30 were ever used on smartphones. The only UI used with Symbian from what you mentioned was S60 and yes, it didn't have a reputation of being particularly clean. That said, S40 was being used on feature phones for more than a decade (from Nokia 7110 in 1999 up to Nokia 515 from 2013), so it spanned across multiple UI generations and while it was very successful initially, at the end of its lifespan it didn't do particularly well when put on models with big touchscreens.