In speaking on this subject, I would like to make the distinction between the two Clone Wars cartoon series. The first was a traditionally animated series by Genndy Tartakovsky—a very talented artist responsible for the very unique 'Samurai Jack' series. The second was the 3D-Animated series created by Lucasfilm's own animation studio.
Both series take place in the time between Episode II: Attack of the Clones and Episode III: Revenge of the Sith. Both series deal with the exploits of Anakin Skywalker and Obi-Wan Kenobi during the war against the separatist confederation, led by Count Dooku, General Grievous and Asajj Ventress. And that's really about where the similarities end.
Tartakovsky's series was highly-stylized and simplistic in its presentation, focusing more on motion and mood than on detail. The series' plot was almost entirely action-based, with only brief moments of dialogue and character interaction between sequences. But despite this, the storytelling was masterfully done. Characters were given depth by their actions as much as their words. Memorable sequences include Anakin and Padme's farewell at the start of the Clone Wars—done entirely without dialogue, where Anakin presses his metallic hand against the canopy window of his fighter as Padme watches from afar. Even as simply drawn as the characters were, you could see the emotion with just a few drawn lines- the downward curve of their mouths, a furrowed brow. Anakin's Knighting ceremony is likewise emotional, and equally light on dialogue—you see the simple pride in Obi-Wan's eyes as he looks on, and the excitement and gratitude in Anakin's as he looks back. It is understated, but understandable. It is subtle and feels 'real'—a strange irony considering the over-dialogued live-action movies that book-end this series.
The action in this series is likewise well done. It is fast-paced and visceral—characters move /fast/. Things develop /fast/. You don't have time to ponder what will happen next because it already happened. Anakin's first duel with Asajj Ventress is a prime example of this. It is intense and brutal, and makes clever use of Force powers (such as when Ventress hurls a large stone block at Anakin, only to be surprised when he slings it right back at her). Likewise, when Shaak-Ti is battling Grievous (and getting beaten badly) she manages to slyly tie his cape to a train-car using her telekinesis—and then activate the train, yanking Grievous along with it. We're shown new and interesting ways of Jedi fighting: like Yoda's massive force-pushes, clearing out entire swathes of battle droids, and Windu's unarmed technique, where he destroys dozens of droids with just his fists and feet and even an unnamed Ithorian Jedi's force-enhanced sonic-blast. It seem like Tartakovsky is indulging in all the 'what ifs' of being a Jedi, showing us things we haven't yet seen before. My only criticism of this is that sometimes, the Jedi powers are just a bit too much to believe (even if they are visually interesting)—I mean, Windu 'riding' a captured droid fighter, steering it via wires he ripped out of its access panels? Just a bit over the top. Again, there is a strange Irony in all of this—because in the live action movies, we only really get 'more of the same' when it comes to fight scenes.
And finally, one of the places where this first animated series shines is its treatment of the villains. You get to see a bit more of Count Dooku, his ruthlessness being grandly portrayed in one sequence where he dispassionately watches an entire arena of viscious beings slay eachother for the chance to be his disciple. The winner of this competition, Asajj Ventress, is then brutally beaten by Dooku just to remind her of her 'place'. It both shows just how cruel Dooku is, and how powerful.
General Grievous is given his grand introduction to the Star Wars mythos in these cartoons—and what a memorable introduction it is. He has a group of Jedi pinned down in a crashed starship. They still aren't quite sure what they're up against. One of the padawans can no longer take it and charges out, only to be literally crushed beneath Grievous' taloned feet. From there, he goes on to decimate this entire group of Jedi, all by himself. Only the timely arrival of a special squad of clone commandos saves some of the Jedi. Even as Grievous flees, one of the Jedi Masters is frantically ordering the Clones to kill the general before he can escape. To see such fear in the actions of a formidable Jedi really drives home the point of just how big a threat Grievous really is. This is only reinforced by the scene near the end of this series when Grievous breaks into Chancellor Palpatine's office. Several Jedi flee with the Chancellor while the clone troopers try to hold Grievous off. The battle is once again sharp and brutal—though we as the audience see only a portion of it. In a truly inspired move, Tartakovsky moves the camera out into the hall, where the Jedi wait anxiously for the elevator as the sounds of horrific combat come from beyond the office door. At one point, one of the Jedi hastily mashes the 'call elevator' button over and over, trying to make it arrive faster. This is funny, sure, but it also helps show the fact that the Jedi DO fear Grievous.
In watching these Cartoons, I feel almost short-changed by Grievous' appearance in the movies. All he does there is run away and get defeated. It's sad, really, to make a character who could have been a truly terrifying opponent and reduce him to a card-board-cut-out who just looked a little scary. But then, the movie didn't really have any time to spare for Grievous—which makes me wonder why they introduced him at all. They could have just kept Dooku around and developed his character...but...oh well.
Before closing, I would be remiss if I didn't mention another very artful and powerful moment in this first animated series: It is a 'vision quest' that Anakin takes on the planet Nelvana. He goes into a cave and finds a series of paintings on the wall that represent stories from the natives past. The primitive paintings seem to come to life in Anakin's vision, telling the story of a being who gains a strange power which he uses to defend his people from evil—even at the cost of his own hand. The story—told entirely with this cave painting style—continues with the hero's power being perverted, turning against both the people he tried to protect and himself. In the end, it destroys his family—and as the 'dark power' spreads across the wall of the cave you see the stylized image of Darth Vader's mask growing within it. Again, all of this is done without dialogue, but its meaning is creepily clear to everyone. Even Anakin seems shaken by it. I know a lot of criticisms of this series come from the stylized artwork of it, but honestly? You don't need more than this if you have a solid story and know how to tell it visually.
Considering the length of this post, I'll continue later with my discussion of the second (CG) animated Clone Wars series. Yes. That is the sound of the other shoe about to drop.