jailbreaks usually tend to trail apple's official updates... which means you are likely to have an outdated version of the OS. that's still ok, but at least in initial stages of the jb release, user may be burdened with tethering
also, apart from apple's void warranty, apps (especially multiplayer games) detect and ban devices that are jailbroken/ have IAP crackers / trainers installed
also, apart from apple's void warranty, apps (especially multiplayer games) detect and ban devices that are jailbroken/ have IAP crackers / trainers installed