I have the 30 day shred, and I would say just stick with it until the "end" of the program so that you can give it a fair shot and see if it's something that works for you.
I like it becasue its short... Painful but short. I did set some really high goals for myself in the next month, so I also do the "Couch to 5k" progaram (free app that you can download onto your phone that gets you to run 5k through a nine week training program).
I find that there are a lot of great programs and dvd's out there, but they only work when you actually do them the way they were meant to be done. So give Jillian a fair shot, and at the end of the program you can decide if you want to continue or not.
My personal favorite (and I killed the tape with overuse and after years of searching, just found it online on Amazon and Ebay, and now impatiently waiting for it's arrival), is an old workout (1h) from 1988 by The Firm, it's Low impact aerobics with weight, with Janet Jones. It's hard, and it really gets you sweating, but because it's low imact aerobics you don't feel like you are going to die all the time. You can see clips of it on YouTube, but be warned, the outfits... Well... It was shot in 1988. I HIGHLY recoment it. I have tried a lot of things since then, but NOTHING and I mean NOTHING has ever done to my

- ahm, behind - what this workout did. Hands down my favourite!