/advisor is like the old /opusplan mode but for running tasks not just pre-planning. It can work nicely with Sonnet as the main agent and escalates to Opus as needed.
Advisor-mode has been very helpful indeed, I can now plan with Opus, have Haiku code, and escalate back to Opus for review. It’s a decent flow for Pro subscribers trying to max their usage. But as I’ve said above, sometimes it’s not worth it: Sonnet and Haiku can produce stuff that’s not worth reviewing.