It requires you to provide a phone number (read disclose your identity) to use it. And its homepage has the word "privacy" repeated several times. It looks like a poor joke.
The alternative (using Telegram's homegrown and dubious cryptography and lack of actually encrypted group messages) is significantly worse. Here's a nice summary of the issues: https://security.stackexchange.com/a/49802/43733
IP address is much easier to hide, for example by using a VPN.