I've had a jailbroken iPhone since the very first hack into 1.0 and never have I lost any information or had to restore. Me thinks people jailbreaking need to know how to do it right instead of complaining to other people about their own short comings.
A large percentage of iPhone owners are windows users that barely get by on clicking the green start button, much less modding a unix/linux operating system. The windows guys that DO know what they are doing aren't experiencing problems, but unfortunately that is few and far between as most use windows for a reason..... they don't know linux/unix. They buy a phone, try to hack it, screw it up, .........complain to someone else about how THEY screwed the phone up, no.... not the person doing it, the person who invented the jailbreak that works for the other 98% of people that can pull it off without a hitch. That's the problem right there. Congratulations, you've figured it out!
Theese are the same guys trying to stick 1.1.1 apps on a 2.0

OS.

It's bad enough to not know the operating system, it's worse to see people SSH'ing RBST 1.0 into a 2.1 FW (I swear...... I've seen it happen)
Jailbroken apps work fine with no problems. Cracked apps are nothing different from app store apps, they just have the DRM forced to accept any user so they'd work as APPLE intended them to (ironically). Poetic justice though if you steal an app and your phone crashes.... can't help but love it. I use paid apps and jailbroken apps. I have no need for cracked ones as mine are bought, but no different than the guy next to me that stole his.