My son and wife have one. My son's has already been replaced by Apple. My wife's continuously locks up and usually just needs to sit away from the charger for a day and then it works again.
beware ipod
My inital experience with the new 40gb ipod was excellent but the honeymoon is over! The unit has completely died after only several weeks of use. Numerous glitches forced me to constantly "reboot" the unit until it stopped working completely. Battery life never came close to the claimed eight hours, plus you are unable to back-up audio files from the ipod thanks to apple becoming a lackey for the music industry. I really feel like I have been taken to the cleaners on this purchase. I spent the better part of a week loading .wav files onto the unit and to have it completely crash so quickly means that apple obviously has some quality issues. The ipod is based on an off the shelf Toshiba hardrive that retails for a couple of hundred dollars so you are paying apple for the interface and the cute plastic box. I love electronics and have spent a fortune on them over the years but no purchase has been such a huge disappointment. Avoid the temptation to buy what seems like a great unit. Steven Jobs has no clothes.