After reading an overwhelming amount of glowing reviews for this mouse online, I was dead-set on buying it. I've used it for almost a week now, and I can confirm that the mouse is indeed worth the price and does not disappoint the hype it's generated.
I've been using a SteelSeries Sensei for almost 4 years now after I started getting terrible wrist pains from constant use of more "ergonomic" mice (prior to the Sensei, I was using a 1st-gen G700 wireless and before that, the 1st-gen G9). I claw my mice, so most ergonomic shapes had a weird effect on my wrist for whatever reason. I used a standard ambidextrous mouse at work and noticed pain wasn't present during the use of it, and that's how I ended up switching to the Sensei. Anyways, though I loved the shape and customizability of the Sensei, the software always had weird quirks (the automatic switching between profiles based on detected games/programs was hit or miss more often than not) and it was a little inconvenient having to configure my devices from two separate program. I waited for Logitech to develop a mouse with the same design and button layout as the Sensei for what seemed like forever, but I'm glad I did. Customizing the buttons/lighting via the Logitech Gaming Software was just as straightforward as it is with their other gaming peripherals, and the automatic profile switching was very reliable. The mouse also has the ability to store a few profiles internally if LANing is your thing.
Overall feel of the mouse is great. The left and right button clicks have a satisfying click to them, almost reminiscent of striking a key on a mech KB. You can choose to have the two side buttons on the left only, two on the right only, or have all four side buttons at the same time (which is my current setup). The buttons are secured/removable by way of a small magnet that holds on to small metal points on the buttons themselves. I was initially afraid that i'd lose a side button because of this design feature, but was pleasantly surprised to find that the magnets themselves were pretty strong at keeping the buttons secured. Those side buttons are also pretty satisfying to click, though maybe just tinge less clicky in my opinion. Scroll wheel has nice solid clicks, and can be changed to a free-scrolling wheel with the push of the button directly below it (one of my favorite features in some of the modern Logitech mice). The skates glide pretty effortlessly on most surfaces, and combined with it's relative light weight, makes it a pleasure to wield. I recommend using it on a hard surface mouse pad.
The wireless connectivity is also another one of its high points. Most people don't associate wireless mice with gaming, but I think this mouse makes a strong case for it. I play a lot of games that require quick, sudden movements (DOTA 2, BF4, Overwatch), and have not noticed any type of latency or input lag between the mouse and my games, which is great. I also haven't noticed any broken connections/interference with the wireless either, which was surprising considering the plethora of wireless devices in my home.
Battery life is pretty awesome. I've been gaming for about 3 hours a day on average the past week and have yet to charge the mouse (I charged the battery to full as soon as it was unboxed.) The battery level can be seen via the Logitech Gaming Software, and you can also bind one of the mouse buttons to display the remaining battery life as well.
Despite it's high price, this mouse is still extremely solid and will prove to be a valuable asset to your gaming rig setup. The excellent button feel, reliable wireless connection, and integration with the Logitech Gaming Software makes this mouse almost a must-have for anyone wanting a high quality experience in their mouse.