I've been listening to Paolo Nutini ever since I first got the FREE iTunes download from his debut album in 2006. This is a lot longer than usual for me to stick with an artist (uninterrupted), especially as most of my musical tastes have transformed significantly over time. What helped keep my interest in his music was that Nutini ALSO transformed over time.
His first album (These Streets) was, for all intents and purposes, a mellow folk/pop album. It's nice, easy listening.
Caustic Love was released on Atlantic Records in 2014 - this time he was exploring something different. This album is much more rooted in R&B and soul, with clear influences from artists like Marvin Gaye and Janis Joplin. The vocals aren't as balls-to-the-wall as some of the great soul singers but it's a different, gentler vocal style with the kind of raspy Joplin-esque quality that I really love.