Thats crazy, Is there a downside to jailbreaking the phone?
The apple fanboys will scare you into thinking it will ruin your phone, but there's no real danger there.
Worst case scenario, you can restore you phone to factory settings, and if you backed it up, restore from there.
I guess it could be a pain in the ass when Apple releases an OS update, but that happens so rarely, and frankly I can't imagine them coming out with anything must have that I can't get already on my jailbroken phone.
Even if they did, after a couple of weeks they'd have the jailbroken apps updated.