* Colored nick-names
* Theme-ability, even if only through user-provided CSS overrides
* Nickname autocompletion when hitting tab, preferably with some logic such as "you talked to this user recently"
* A locked down mode in which only authorised users can connect
That said, I really like the fact that you can search the history right from the client. Since I am not using this in production, maybe someone with more experience can tell me about how well it scales?
Also I feel that the separation of channels and DMs with users is very sensible.
I personally use The Lounge (https://github.com/thelounge/thelounge) for my web IRC needs, which solves my main issues outlined above, but doesn't have searchable history nor separated users and channels (there might be a setting for this that I haven't found yet).