I was apprehensive to take the plunge on this, thinking that there surely couldn't be a justifiable performance benefit worthy of the extra cash spent on this mat. Being one who is willing to try new things in the name of comfort however, I decided to give it a go. I am very pleased overall and have used this not only for gaming, but also in the office where I spend long stretches of my day mousing vigorously.
This mat has a surprisingly low amount of drag, which adds up over time. I feel less fatigued than before when using this mat in long bouts. Paired with my Logitech mx518 I certainly have the most comfortable mouse setup in the office, and it has met or exceeded my expectations for home/gaming use as well. My only caution would be that after transporting to/from work constantly, the edge has begun to fray to a small degree; for this slight shortcoming in durability I have to deduct one star.
Overall I am quite pleased but given the price I would have hoped for the construction to be a bit more robust.
Edit: Having purchased a second one of these, I discovered that Razer have begun to stitch the edge of this mat with a strong string which prevents fraying and feels comfortable under the wrist. I have raised my rating from 4 to 5* to reflect this.