Drove mine for 30 miles today, roof down, hat and gloves. Warm. Fab Fun in an old school ‘hang on tight’ way (and that’s from someone who’s owned a Boxster, Lotus, Z4).
Heater should be fixable. That said, with the blower on mine only registered 1/4 temp today (cold day) despite being driven hard (aside from a 1 minute breakdown…dodgy coil spade connector).