An operating concept you have to - if you umsteigt of a classic mouse with scroll wheel - safely used to. You move not only a key, but the entire surface of the mouse clicking. Whether you click left or right now, will be decided based on the position of the finger when you click, what works well. If you get used to scrolling by wiping on the mouse surface, and (depending on your taste) the other gestures, a wheel mouse feels somehow dowdy.
Not so well resolved are "special functions" as the middle mouse button: to tamper with two fingers at the bottom of the mouse is cumbersome, and that will probably also nobody do in practice. Worse, if you want to click at the same time with two keys - that's not fact. Anyone who works with software that requires a middle mouse button, or even a right + left-click, will have to look for another mouse. Personally, I have for a long time used no middle mouse button, and right and left at the same time I had to click in any program I know. Those are in my view special features that are not needed by the majority of users, and thus have no effect on my rating.
The visual similarity with the (twice as expensive) Logitech T620 is actually not a coincidence - it seems to be at exactly the same hardware, the distinction was purely determined by the software that was originally cut by M600 arg (eg was horizontal scrolling as touch gesture is not configurable). This distinction has since been repealed but Logitech - who installed the latest version of Logitech SetPoint software, gets the M600 all functions of T620. So there is no reason to buy the more expensive mouse.
Supplied in addition to the mouse itself and the Unified receivers are also a bag containing (for example to protect the laptop bag) and two AA batteries.