By recommendation of a regular reader, I have just watched the old Cartoon Network version of The Clone Wars.
You can read my review of the new Star Wars: Clone Wars here.
The old one is all in Cartoon 3D animation, whereas the new one is created with modern CGI animation, which should mean that the new one is a lot better... but because the old one is made a lot cheaper, it has to be very good on the story-line (which it is) thus turning it's curse into a blessing.
The new Clone Wars' story-line is so weak in comparison to the old one.
The old Clone Wars much better deserves the right to bear the name "Star Wars". And I'd certainly recommend it as a better alternative to the new Clone Wars (which I rated very low).
The old Clone Wars seems to fit in much better with the Star Wars storyline, filling the gap between the 2nd and 3rd episodes. Characters are much better developed too!