I have been using kali linux for last 5 years. This is unix based operating system. We can operate in both text mode and graphics mode. But I like the text mode. Anybody who wants to learn hacking then this is the best operating system to start with. Kali linux have so many tools available which can be used for hacking. Aircrack-ng is the most popular tool which is used to explore the wifi password. WIreshark is used for network spoofing. Other useful tools are also there which come inbuilt with this packege. Kali linux is very easy to use. This is very user friendly just like Ubuntu. Installation is very easy. And the packages can be updated easily.