It's been two years since I started painting miniatures. I've really only been "painting" a year though. The first year was rough. I want to toss some of them in the trash. Prior, I wouldn't have thought I would enjoy it at all. I've learned quite a bit from the process: (thread)
1) Most important! The painting process grounds me in the theme of the game more. While I'm "creating" the character, the decisions for colors... trigger story telling moments. The painting process can very much be an integral part of the game-play and narrative directly.
2) Painted models actually did make the games more enjoyable. But... only after I started painting. Prior to picking it up, I was just fine playing games with unpainted models. But now, it's as if I've ruined that experience for myself. I immediately have the urge to "fix" them.