I kinda felt that way too, mostly because my JB experience with iPhone 4 wasn't all that good. I think it was because I loaded so much on it though and played with many themes. I think it caused conflicts. Nice thing about jailbreaking however, is that you can changed as little as you wish. So, far I'm not noticing any of the sluggish issues I had with Greenpois0n on iPhone 4. It is all working smoothly, and I love the things I can now do with Siri.
I like the chat feature with Assistant. You can just limit Siri into a chat mode and then when finished return it to the standard Siri. I also like the future possibilities of developing new scripts and applications with this app.