On reflection, and although my position is still that cancellation was a poor decision, it was a thrilling final season with the last two story arcs.
The Super Maul Bros. vs. Pre Visla and later Palpatine himself was an excellent climax of the series in that we actually got to see Palps in action; plus the fate of at least Savage was decided.
Anakin and Ahsoka finally parted ways, making the lead in to ROTS more sensible.
The "turn against the Jedi" is in full swing which adds leverage to the reality of the galaxy turning their backs on the Jedi outright at the end of ROTS.
Obi-Wan almost became a background character, though. I was hoping we'd get one DVD set with him on the cover and another Ahsoka... but with only one release left season 5) it'll be Ahsoka by a mile.