I took it to replace my good old, I would say, the legendary VX Revolution, which worked faithfully for 10 years. On the old one, the left button began to short, double click and does not hold. Wrote in support of Logitech the question, is it possible to fix the button on the old mouse, the second day - there is no answer. For an incomplete day of using the G603, I can say the following: the wheel, compared to that on the Revolution, is complete rubbish. It’s not that it doesn’t work well, but there is no inertia, which is not convenient when scrolling through large texts, and the tactile sensations are completely different, not to mention the lack of horizontal scrolling. The mouse is much larger, the hand is not as comfortable as on the revolution. There is no notch for the thumb, but these are matters of habit and personal preference, although in ergonomics it clearly loses. The most important bewilderment was caused by the HERO sensor at 12022 dpi. Explain to me someone why such sensitivity is needed? Even at 3000 dpi the cursor flies like crazy. If you turn on 1000 hertz polling, then somehow you can follow the cursor, but still, too fast. 12022 - purely marketing, what is its use? I set it to 1200 dpi, as it was on the old mouse, 125 hertz polling is an excellent smooth movement. In general, I’ll still play around with the settings, but the sensitivity margin is clearly excessive. Also, the logic of assigning buttons by default under the thumb is strange: the far one is back, the near one is forward. Reassigned immediately, because it is not logical. In general, in comparison with the previous top-end mouse, it does not cause any enthusiasm. She just works fine.