I like the mouse. It's designed nicely, feels well made, and is just...fine.
Perhaps it's unfair, but I bought this to replace my Performance MX, and the fact that it has the same number of buttons on the side but one can only switch between computers (a useless feature for me), was dissapointing.
But the biggest problem I have with this thing is that the bluetooth performance is abysmal. The connection drops CONSTANTLY. I'll use the mouse to click on a bunch of stuff, type in a text box for 10 seconds, and then go back to the mouse to find that it has to wake up again and reconnect. It's extremely annoying. I can only imagine that this is baked into the hardware to allow it to achieve the battery claims on the package. But the result is that it's functionally useless to me. This mouse is actively slowing me down because I have to wait up to 5 seconds for it to wake up nearly EVERY TIME I go to use it. I would be ok if it did that after anything more than about 5 minutes of non-use, but it does it after the briefest pauses sometimes. It's just obnoxious.
I have now bought the Logitech G604. It's also using bluetooth but it has none of these problems. I can pause for brief periods and go back to it with ZERO delay in movement. Other times I'll come back to it after typing something for ~5 minutes, and it takes *gasp* about .5 seconds to wake up. I threw away the packaging for the M720 otherwise I'd return it. I guess I'll use it as a spare and throw it in a drawer somewhere.