Sì, ho auto modo di guidare anche la 575. Entrambe bellissime macchine, senza dubbio.
The 599 clearly is a completely different car compared to the 575 under many aspects: all-aluminium chassis and body, magnetorheological shocks, Manettino settings, Enzo-derived F140 engine, F1 Superfast gearbox, etc. It definitely represented a great evolutionary step in the technical and styling fields.
The 575 still offers a hint of analog feeling, a feeling that has gone completely lost in the 599, I am afraid. On the other hand, the 599 is a superior touring car, almost unrivaled for cross-continental journeys, and that's the main reason I chose it over the Maranello. 599's F1 shifts are considerably faster and sharper, too.
As for the performance,
They are both very powerful and very nervous cars. The 599, though, is frightening, on the borderline of being unsafe. Drive responsibly.