I just got mine from the original pre-order today. Thought I'd be waiting well into 2015. Here's my impressions after 30mins.
I've only opened one of them so far, seems like a decent sample. I am having trouble rocket jumping with mouse2 jump, as other people have noticed. Jump triggers late half the time, and it happens less frequently when i turn right to RJ, so I assume it can be solved by adjusting grip and/or getting used to the force required.
Flicks feel good, tracking feels good. I am accustomed to small/lightweight mice, so there isn't much adjustment period for me. I have been using a Kinzuadder primarily over the last week or two, and this is significantly more comfortable due to the narrower rear putting less pressure on my palm.
Default CPI steps are 800, 1600 and 4000, cycled with the button below scroll wheel. Polling rate is 500Hz out of the box. I wanted to turn off the LEDs, set 800 CPI only and set 1000Hz polling rate, so I had to install the software. After making my adjustments, it crashed when I hit Apply, and the mouse froze. Settings were still saved when I re-plugged mouse, and I have since uninstalled the software. I hear that I am not alone in this.
Scroll wheel is nice and smooth, yet has that satisfying mechanical whirring. If you need a scroll wheel with defined single steps, this is going to give you nightmares. Middle button is decent to click, slightly stiffer than m1/m2, which is about as good as you can get on most mice. Since the wheel is quite slippery, I have caused the mouse to scroll accidentally while middle clicking. May be a problem in TF2 where I use scroll wheel up/down to select slot2/slot1.
Lift-off distance is low. Not the lowest I've seen (eg: G502, Zowie), but low enough for it to not be a problem. I am a big fan of low LOD and this is acceptable.
Glide is fine, despite feet being a little thinner than I generally prefer. I don't think I would personally want a faster glide, as more friction tends to help stabilise light mice for me.
Cable is okay. For me it's similar to G302 and WMO level of thick/heavy. The texture of it is largely irrelevant for me, because it doesn't touch my pad at all. The cable is stiff enough that I can actually get it to suspend itself for about 25cm distance from the mouse to my desk in front of the pad.
Polling rate at 1000Hz is very consistent (largely within 0.5%), BUT every 15th (why??) update is 2ms/500Hz. I doubt this has any serious impact in general gaming usage.
Regarding side buttons, I don't really use them. The front one (mouse5?) is great, the rear one (mouse4?) is a little more difficult to get to with my grip. The only game I currently use a side button for is TF2 (slot3). If you need both buttons often, you may find you need to adjust grip to suit. The thing about squeezing the shell to activate side buttons never comes up for me in actual games. You REALLY have to squeeze it quite deliberately and hard. HARD.
Also the lights have that PWM thing going on, where you see stroboscopic artifacts while moving the mouse. A lot of mice do this. I turned all the lights off.
Anyway, main points TL;DR
+ Everything I want in a small, light mouse.
- Software buggy for me
- mouse2 feels delayed sometimes for some reason, likely grip/force related
Next step is checking my other sample to see if its better/worse, and deciding which one to put inside a WMO shell.