Was driving my mother's Z4 to work the other day when the flat tire monitor light went went on (red light, looks like a tire). I was able to drive the 20 miles to the dealer to get the car checked out. BMWAssist called ahead for me to setup the appointment and get a shuttle ready to take me to work. The only thing I really noticed was braking was a little bit sluggish (or soft).
Turns out I had a roofing nail in one of the tires. For $26 the dealer was able to repair the tire (patch from the inside) and I was able to pick my car up by lunch time. Plus I got a car wash, and cleaned out the interior.
Without runflats, I figured it would take several hours to get the car towed and checked in (during morning rush hour). Then I would have been late to work and who knows when I would have been able to pickup the car. Punchline of the story: runflats good.

Looking forward to my E90 with runflats!