1. It doesn't void your warranty, DFU restore and you're set. 2. Most things do not cause the iPhone to lag considerably. Like everything else in life, use it moderately. 3. I can upgrade to the latest firmware in less than 48 hours, which actually allows me to have time to read others' feedbacks on the new firmware before I take a dive. Upgrading is easy, downgrading isn't (if possible at all). 4. AptBackup backs up most of the jailbreak apps, similar to how iTunes backs up purchased applications and preferences. 5. I can always restore or remove apps if my phone is laggy or slowing down. 6. Most themes can make the SpringBoard look crazy cool. 7. I've found that most things in life are cool at first but quickly get old fast. But JB is definitely cooler than stock. 8. SBSettings. 9. Apple is slowly loosening their grip on what the developers can do, but there is still a long list what they cannot. 10. Because considering how this list was formulated, you should really question the source.