I've heard from one person that their phone locks up now and then with windows...
Palm is no rock-solid OS either. I've had a 650 for 2 years now. If I don't count the crashes caused by the opera mini web browser (almost daily. why does it lock up if you touch the screen while loading a page...), I'd say my 650 crashes a few times each month. I can't comment on the 700w although I've had regular windows pocket pc's and they never crashed on me. Overall, having the 650 + adpl is well worth the money.