I actually have one, and I'm not very happy. None of the problems mentioned above are actually issues, what is an issue is the buggy Synapse software/driver.
There is a DPI clutch button (you can't see it, it's on the side right where your thumb rests) and it doesn't work well at all. It's supposed to be a "press and hold" feature to reduce the DPI, but sometimes when you release the DPI doesn't go back up, and sometimes it just sits there and freezes for a couple of seconds, then works again. It's not a wireless issue either as it doesn't happen if you don't use the button.
Furthermore, the mouse displays on the screen the DPI change when holding/releasing that button. Randomly it will move from the right side of the screen to the very bottom left. You can't move it and you can't turn it off either.
Perhaps a software update down the road will make this guy live up to expectations, but their software is already bloated and slow.