IRC to Discord is an easy transition: you join servers via invite code, the servers have channels, etc. There's a very slick web version and clients for pretty much all platforms. They've kept a bunch of IRC commands like /me, /nick, etc.

The blessing and the curse is that it's a centralized behemoth of a service--everything lives on Discord's infrastructure--which means low latency, no downtime, no channel takeovers, and no netsplits, but does make it vulnerable to takedowns and venture-capital backers demanding aggressive monetization. So it's kind of "enjoy, but don't trust for the long-term."