Your phone is doing better than my iPhone! (4S, 64gb, latest FW, not JB)What crashing? My experience with Windows Phone 7.0/7.5/8.0 has been one of utter stability. Maybe 2 crashes in 18 months.
That thing crashes once a month, including a crazy bug where it sometimes doesn't hang up a call. I have to shut my phone down to fix it.
I'm interested to see what comes of this. My girlfriend has a Windows/Nokia phone from last year and it's a sweet little phone.