I have no experience of "bluetooth" mice (sounds like something DEFRA would be interested in) but have long had standard RF wireless keyboards & mice.
I find the lack of tail a positive bonus, as it no longer gets tangled up with other wires on my desk. I still have a standard wired mouse at work and it's always getting knotted up with my telephone headset wires.
I not sure of the benefits of wireless keyboards, seems like a total waste, because it's not like you move them around so much that the wire gets in the way.
I now use a laptop at home, so I just have a MS wireless optical mouse, I've had it for about 6 months now and not had to replace the batteries yet.