Pros: The MX Blue switches feel so nice. They are very clicky. I work on the phone a lot and people mention how loud it is occasionally, but I like it because they know that I'm working when my keyboard is clicking away. The media functionality is fantastic, I absolutely love the volume wheel. Build quality is superb.

Cons: The price, but it was so worth it especially for a keyboard that will last this long.

Pros: the one i'm using has the brown switches. i preordered it through das, and wanted to write a review about how amazing the keyboard is. i had the older professional das s version with brown switches as well, but this keyboard is far superior.
-usb 3.0 with nkro
-media buttons/volume knob are awesome
-cherry browns: i've had blacks and reds, but browns are the sweet spot for me
-build quality: i've owned filco, steelseries, das s, logitech, rosewill; the das 4 is superior in every way
-gaming: just incredible
-magnetic ruler? i haven't used it yet, but i guess it might come in handy
-other thoughts below

Cons: none so far

Other Thoughts: i was worried that the edge around the keyboard would be sharp and get in the way. my wrists never actually even touch that part of the keyboard so it's a non-issue. the volume knob is exquisite. it makes a small sequential click noise, almost like a mouse click. i've used the media buttons while using itunes, and it's both instantaneous and seamless no matter what other program i'm using. the overall quality and ease of use is absolutely worth the cost of entry. there's no extraneous features, just exactly what you need in a quality keyboard. this is an amazing keyboard for typing, gaming, and everyday use. i don't want to stop writing this review because it's that enjoyable to type on. combined with my Func mouse, i feel like i've found the perfect combination.

Pros: Great keyboard for the price, truly professional, and amazing build quality.

Cons: Only one con I have found so far. Sometimes the keyboard does not work at all (happened twice) and I'll have to unplug and replug the the keyboard.

Other Thoughts: Other than the one con this keyboard is flawless.