What's great
Ran my retirement numbers through this last nigth. The Monte Carlo engine is legit. 1,500 iterations plus historical crash scenarios applied to your actual portfolio. That's not something I've seen in other FIRE tools.
What got me hooked: I modeled Munich full-year vs splitting time with Cape Town. The cost delta alone buys me almost four extra years before the money runs out. Seeing that quantified with real IMF inflation data per country instead of a flat 2% assumption was an eye-opener.
Architecture note for the technical folks: everything runs client-side, data stays in localStorage, no backend. Clean approach for a financial tool.
What needs improvement
One thing I'd want eventually: JSON import/export for scenarios so I can version my assumptions outside the UI.