One of the best, to me only Beast Wars beats it in terms of characters and story.

The show was slow to start, but afterwards picked up and got incredibly interesting, Season 3 is one of the few tv series where I could happily watch the whole season in one go. (Avatar TLA, TMNT, Arrested Development are some of the others). Some great change ups, and different characters an character interactions. Some Autobots seem more like cons and generally the Autobots aren't painted with the "perfect hero" brush. Nice spin.

The comics were fun, but mostly irrelevant.

The Allspark Almanacs were brilliant and should be hunted down by every fan.

The toyline was interesting. Hasbro, in their wisdom, decided to cut costs and change factories. Animated figures suffered from a myriad of QC issues, bad paint applications. figures were loose straight from the packs and generally did not feel as well made as the Cybertron figures. This was a big disappointment since some of the toys are among the best made in any line prior, or since.
QC issues aside, some toys were hampered from the unique style of the show, the voyagers in general were small, Lugnutz and Bulkhead for sure. Blitzwing was just a horrible toy. The deluxes were well made, and of varying sizes, from the giant Blurr, Oils Slick and Lockdown to tiny Swoop and Black Arachnia. The activators were a welcome addition, roughly scout sized with the flip-former transformation from Beast Wars back. The leaders were excellent, and another nice surprise, no Optimus in that size class, there was however a Supreme size Optimus with an Auto transform gimmick.

Japan released a number of figures that Hasbro decided not to release: Cybertron Ironhide, Hot rod, Arcee and Blackout, all are brilliant. Hunt them down. Not manufacturing other figures such as Omega Supreme, Red Alert, Spittor the Constructicons etc was idiotic, and another negative of the live action movie crushing the franchise.

Animated was a great series, cancelled before its time. It had to deal with hasbro cost cutting and forcing the live action movie upon everyone, yet still came away as one of the best series/franchises in Transformers history. It seems, like Beast Wars before it, when Hasbro are onto a good thing, they cannot help but rush it to an early demise, only to replace it with a giant, steaming turd.