Okay, the mouse for anyone familiar with TrackBall is by far the best I have ever used and recommend.
70+ is definitely not a small amount of money for a mouse, but you save movement, fatigue, and maybe in many applications it is better than the classics like drawing, for example.
It has a button next to the "ball" that, when pressed once, makes the pointer movement infinitely slow to allow you to move in detail. With another press, it deactivates and returns to its default speed (which you can adjust either from the computer settings or from the Logi program).
The ball comes out easily and cleans easily, as does its recess.
It has 2 extra buttons to the left of the left click (forward, backward, etc.) which you can customize for other functions.
It has a switch on top to switch between the 2 channels it has, 1BT and 1dongle (2.4), compared to the previous model where you had to lift it to change it because it was underneath. The only positive thing about this was that you didn't accidentally press it, but having it on top is clearly more convenient so you don't have to lift the mouse and you just get used to not pressing it randomly.
The central scroll wheel also has extra clicks to the right and left, in addition to the central one.
And finally, it has a very nice, stable, and compact base underneath where you can choose between two inclinations for the mouse to sit on. The classic one (like the position of the old model) and another inclination that provides a better, more ergonomic, and comfortable position for the wrist.
Even if it cost 100 euros, I would still buy it and highly recommend it. In general, since I got the trackball (its predecessor), I have never changed my mouse, not even for my work (IT). The only case where it has not been able to replace the classic gaming laser mouse is in shoot em up games. It does everything else better, maybe even more.
Well done, Logitech