I went into this thinking it wasn't going to be a big difference, to be honest I was shocked.
List the keyboard I've had a chance to use (for extended periods of time) in the past few years in no specific order.
Logitech G15
Saitek Eclipse I and II
Logitech UltraX(Scissor Switch keys)
Logitech Wave
Z-board
Generic Dell and HP
Many different laptops
I've also had a chance to use a Lycosa and the Tarantula from Razer. But no extended
time with them.
From the reviews I read about quality control being an issue, I can say I don't have any keys that are hard to press any keys that are working intermittently or any other issues people have talked about in the reviews online.
Comparing it to my most recent keyboard, the Logitech Wave, well...There really isn't any comparison, the M10 feels completely different but in a good way. It really does feel different than any keyboard I've used.
The feedback provided from the Cherry MX Blue switches offers both an audio feedback as well as the tactile feedback. I first purchased it I was worried that it would be harder to press than any previous keyboard. Completely wrong, if anything these feel like the correct pressure to press keys with.
When first typing on the keyboard, the difference is quite substantial. I found myself enjoying how the keys felt and the sound they were making, confidence in each keystroke.
To the claims that this will make you type faster and more accurate, I could actually see that. But with my short time with this keyboard so far, I'm not sure if there's been a difference or not. Through the typing test, I did average a few WPM more upwards of 85-88 through all the test compared to before 78-82. That may be due to how tired or awake I was at that moment. More testing will need to be done after I've grown better accustomed to the M10.
I let both my room mates use the keyboard, they both agreed that it feels great, but I didn't give them a long time with it.
I really don't see any reason to say this isn't the best keyboard I've used to date. Keyboards are really a personal opinion, and this is mine. I hope to be using this keyboard for a long time, if the keys feel the same in a year, then the price was definitely warranted and I will be extremely happy with my purchase.
Box:
http://img.techpowerup.org/090610/IMG00057.jpg
Keyboard:
http://img.techpowerup.org/090610/IMG00059.jpg
Size Comparison:
http://img.techpowerup.org/090610/IMG00060.jpg
Sorry for the blurry pictures, I don't have a camera so phone pictures will have to do.