Radare3 is the one and only interactive, programmable, extendible, multi-processor disassembler and debugger you will ever need to use!
Installation is as simple as it gets:
$ sudo ./install.sh
To start r3, simply run:
$ r3
Or for the 64-bit version:
$ r3x64
And you'll be prompted with the brand new state-of-the-art radare3 GUI: