its worth it as long as you feel its affordable.
my friends are basically seperated into these two camps
1) Bought it, use it once or twice, like it, think its cool, but never use it continuously. (for one, the BT headset needs to recharge too, the battery life is probably worse than your cell)
2) Use them religiously. These ppl usually bring the BT to work and leave the cell phone in their drawers or handbag, while leaving the headset on for the whole day.
there are aftermarket BT headsets (like, non-Nokia non-SonyEcrisson ones and they are good and cheap too)