We've started to be an early user in December and have since adopted it in a brown field codebase. I'd describe this as Lovable 2.0 or vibe coding 2.0.
The p0 workflow allowed us to delegate medium to complex full features to Claude Code while staying in lane with our standards. It allows us to go from idea to fully working prototype and PR within half and hour to hour, most of the time fully hands off.
PRs still need to be reviewed for production. However p0 allowed to drastically improve per engineer velocity, AI code quality and iterate faster with working prototypes and refinements.
Compared to Claude Code directly, which we also use heavily, p0 keeps very strong coherence from user story, spec planning, architecting, engineering and QA - across many several agents and subagents. Breaking down the work into sequential and parallel task. With Claude Code alone this would be usually requiring lots of hand holding, or be be only partially focussed, rest lost in the woods. Also, we attempted to replicate some of p0 ideas with home grown software dev personas and workflows which fell apart. I think the strong point of p0 is that they really nailed the decomposition and software dev cycle with agents.
Really recommend to try, and at the very minimum you get to make your codebase agent ready if you haven't already.