Why Whatsapp sucks!

Whatsapp claims to protect privacy, but damn, did they get it all WRONG!
I mean, which privacy is worth keeping:

1. The safety from advertisements in your messaging application which might potentially make your application free for you to use.
2. The sharing of your number with potential stalkers within your workgroup or friend circle. It's like your phone number today, is some kind of public property where anyone can get access to your phone number just by being on the same group as you.

The next problem is continuing the conversation, especially since once you change your phone number, and use a phone which doesn't have all your old contacts, it essentially means that you need to start using Whatsapp again, from the beginning.