When comparing ii vs IRSSI, the Slant community recommends IRSSI for most people. In the question“What are the best IRC clients for UNIX-like systems?” IRSSI is ranked 3rd while ii is ranked 9th. The most important reason people chose IRSSI is:
Screen multiplexing and remote connection options with screen or tmux.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Everything is a file
ii is a minimalist FIFO and filesystem-based IRC client. It creates an irc directory tree with server, channel and nick name directories. In every directory a FIFO in file and a normal out file is created.
The in file is used to communicate with the servers and the out files contain the server messages. For every channel and every nick name there are related in and out files created. This allows IRC communication from command line and adheres to the Unix philosophy.
Pro Terminal-based
Screen multiplexing and remote connection options with screen or tmux.
Pro Themes
Allows the modification of IRSSI's look and feel.
Pro Free and open-source
Pro Quick and easy setup
3 or 4 commands and you're ready to chat with all your old friends.
Pro Perl scripting
Allows the user to create and use perl scripts to perform actions.
Pro Command line outputs can be sent to a channel or message
/exec -o figlet "Slant.co"
Pro Easy logging
Pro Persistent connection
Pro Has a plugin for encrypted communications
Cons
Con No GUI
Actually a plus for some, lower memory overhead.
Con Gives little direction upfront
Actually, Irssi.org has it's own GREAT documentation for new irssi users. Inline /help options are pretty well documented.