When comparing Nettalk vs IRSSI, the Slant community recommends IRSSI for most people. In the question“What are the best IRC clients for Windows?” IRSSI is ranked 9th while Nettalk is ranked 12th.
Ranked in these QuestionsQuestion Ranking
Pro Can overlay incoming messages
Nettalk can be set up to overlay incoming messages. Especially useful for games.
Pro Encryption support
Pro Multi-lingual interface
Nettalk is available in English, Spanish, Dutch, Russian, Chinese, Hungarian and German.
Pro Built-in spellcheck
Pro Functionality can be extended via plugins
Pro Free and open source
Pro Perl Scripting
Allows the user to create and use perl scripts to perform actions.
Pro Persistent Connection
Pro Command line outputs can be sent to a channel or message
/exec -o figlet "Slant.co"
Allows the modification of IRSSI's look and feel.
Pro Free and open-source
Pro Has a plugin for encrypted communications
Con No longer developed
Development ceased some time ago (2012)
Con German language
Is primarily a German language client, so the spell check, etc etc is in German.
Con Gives little direction upfront
Actually, Irssi.org has it's own GREAT documentation.
Con Cryptic configuration files
Con Can't do vertical splits
Untrue, there are perl scripts available to do split screens with
Con No GUI
Actually a plus, lower memory overhead