1. It has more depth than the new trilogy.
How does it do that? Simple math, there are 5 seasons with 22 episodes roughly, you get hours and hours more space to tell different stories within the Star Wars Universe and they really go to town. Want to see how the Clone Troopers train or how they defend Kamino from attack? It's here. Want to see hours more Dooku, rebels conspiracy and more? It's here.
2. They re-introduce characters.
Chewbacca! Fuck yeah, he's in as of end of season 3. But then add in a young admiral Ackbar in season 4, young Boba Fett and his efforts to get revenge and even Grand Moff Tarkin (Peter Cushing) and you start to see old characters in new stories which flesh out their characters.
3. They have better Sith
There is a new Sith called Ventress, she can fight two jedi at once, she looks cool, there is conflict between her and Dooku and she has a badass voice actress. She has her own path as a Sith later too, I cannot say more without spoilers.
4. The lightsabre battles are better than the new movies
And there are more of them.
5. You thought Darth Maul was dead?
Well he didn't die in Phantom Menace and you see what happened to him and what happened to his brother series 4.
6. It explores how and why Anakin descends into darkness and the primodial details behind the force
In a multi-episode arc Anakin and co end up on the a nexus of the force with three ancient and powerful beings. Qui Gon Jin even makes an appearance and Anakin and his apprentice are warned of his later change into Vader. You finally get some answers about the force here too - this is essential stuff.
7. It has a Badass Bounty Hunter
Bane is his name and he's like an evil cowboy and his episodes involve heists, jail breaks and kidnappings, as well as murdering children of the force.
8. People die
They get slain onscreen regularly which is a lot to say considering it's on kids tv. No cutaways and sound effects only.
9. It has really high production values
The animation is somewhat skitish till you get used to it, but it is a very high value show and can use its computer graphics to show creative new worlds - and quite regularly too.
10. Anakin is not a pussy.
He's a swashbuckling, leader type who always has his shit together. He and Obiwan are a team and this show is about their and Ashokas adventures.
11. It has a virtual Samuel L Jackson
*insert Shaft theme tune*
WARNING
YOU MUST WATCH THIS SHOW IN SERIES AND EPISODE ORDER, THE EPISODE TITLE IS NEVER SHOWN ON SCREEN IN ANY EPISODE - YOU HAVE TO RELY ON YOUR TV ELECTRONIC GUIDE AND MAY BE AT THE MERCY OF LAZY INFORMATION UPDATERS