I hadn't realised that the long-running TV show had actually debuted with a movie, but figured I should probably watch it before getting started on the actual series. I think that was the right choice, as the film nicely sets up Ahsoka as a character and introduces you to the various extended cast that the series will ultimately follow in more depth, but if you're not interested in the show I don't think the film will change your mind. That said, if you want to understand various plot lines in the show, you need to see this.

Without the film, the involvement of the Hutt clan – and specifically the irritating Ziro – doesn't make a huge amount of sense, as the main plot here revolves around the kidnap of Jabba's infant son. That said, the plot isn't particularly interesting and you could probably pick most of it up just reading a 1-2 paragraph synopsis instead. The script isn't great, pacing is off, and the animation takes a little getting used to. Overall, I'd probably say skip it unless you're utterly devoted to the show (in which case, you've probably already seen it).