Being Optimus Prime's right-hand man sounds like a heavy responsibility, but you'd never know it to listen to Jazz. An enthusiastic lover of Earthen culture (and especially its popular music), Jazz is almost always positive and upbeat. It's not that Jazz is unable to see the harsh realities of the war he's involved in. Far from it. In fact, Jazz is often right there taking part in the most dangerous assignments, doing whatever it takes to keep the evil Decepticons from destroying everything important.
Whatever needs to be done, Jazz not only can find a way to do it, but he'll get it done in the coolest way possible. He's like what the Fonz from Happy Days might have been like if the Fonz was an Autobot (and if the Fonz's jukebox played music from the 1980s rather than the 1950s...).
Jazz has a somewhat unusual distinction among the original cast of Transformers characters. Nearly all of those original characters were officially killed off in the animated Transformers: The Movie, but Jazz was one of a very few that was seen alive at the end. And even among those few, Jazz was one of the only ones to show up in the cartoon afterward. Unfortunately, Jazz was doomed to remain in the background, and his voice actor (the legendary Scatman Crothers) passed away that same year (although, given the lead time necessary to produce cartoons, nearly all of the episodes of season three had already been recorded by that time, so Jazz's relative absence during that season was probably intentional, and not a direct result of Crothers' decline). Even so, those late background appearances demonstrate Jazz's popularity, which has only grown in the decades since.