I've seen some issues with Bluetooth, but not enough to make me dislike it like Tony and Matt. It's all about how well (or poorly) the desktop/laptop in question supports it. For me, it's well worth having over losing my 1 USB port to a dongle (and having to constantly plug it in when getting the laptop out). In any case, I'd like to have the choice to buy their mice in Bluetooth varieties without a bundled keyboard.

As for charging, I have to say I prefer the newer method as well. I've forgotten to drop the mouse at work in the charger before, so I have to fallback to a wired mouse while waiting on it to charge a bit. With the newer Performance MX, I could just cable it to the computer using the MicroUSB cable it comes with, and keep working.