Maybe it's because of Simon Furman's greatest comic stories focussing on the characters, or just because they seemed futuristic and exciting, but I always favoured - a little - the post-movie Transformers over those from the first couple of years. As you can see by a quick look at the various Transformers fansites on the internet, this is a rather rare thing for a fan. For most people, Transformers means Optimus Prime versus Megatron, not Rodimus Prime versus Galvatron.
So, here we have the entireity of the cartoon series' post-movie run. First things first, this presents a vastly different origin for the robots than the comic strip and for a Furman fan such as myself, that presented here just doesn't work. However, if it's accepted that the cartoon continuity is as different from the comic continuity as Generation 1 is from the subsequest generations (in addition, the origins of the Headmasters and Targetmasters, which formed the entireity of the three part fourth season shown here, differs greatly from Marvel's take) this doesn't really matter and the viewer soon becomes swept up into the events.
As a cartoon, Transformers was excellent in differing ways to the comic. Bringing the robots to life on screen allows for some tales to work in ways they wouldn't in comics (a key example being 'The Big Broadcast of 2006' - absolutely atrocious in comic form, but it works just fine here) and, while the cartoons are undoubtedly less mature, less 'real' than the comic stories, taken on its own terms, these are great.
Following on from the excellent movie, however, things suffer a little. The animation is undoubtedly not as good, and the star voice cast of the film (ORSON WELLES!!!) is missed, no more so than with Galvatron. Leonard Nimoy's take was so perfect - maniacal evil personified - that any successor would find it impossible to match.