Whatsapp has three major flaws.



1) It doesn't have an off switch.



2) It won't let you choose whether you want it to autostart or not.



3) To unregister your phone number from Whatsapp you have to send them an email, and they don't check if the sender of the mail is really the owner of the Whatsapp account. So if you're in an evil mood today you can kick all your friends and enemies out of Whatsapp.