Corsair has shown some impressive brand-new products at CES this year, as well as some facelifting on their existing models. The MM350 is in the second category, but this doesn't make it inferior at all. The MM300 was a great predecessor, and as far as I know, it's still available in three different sizes. The MM350 pads add two more size variants to this fantastic lineup.
Unfortunately, I cannot compare the MM350 with the previous MM300 models, but as far as I know, their surface should be entirely identical. The difference is in the thickness and size variants as there was no 450 mm x 400 mm version before.
The surface of the MM350 is absolutely fantastic in my opinion. It's very smooth and silky with very low friction and a tad less stopping power than some of the mouse pads with a similar touch I've tried in the past. It's very close to the SteelSeries QcK Limited in terms of feel, but that one is a tad smoother. The backing is made out of textured rubber and generally should stick the mouse pad perfectly in place. In my opinion, a not as harshly textured, slightly tackier material would be better for the task, but I expect it would raise the price significantly. I had no issues with slipping of course, and I'm sure the mere size and weight of the mouse pad helps with this too.
As for performance, the MM350 has nothing to be ashamed of: it provides perfect tracking with every sensor I've tested. There is a chance some old or low quality sensors will act up because of the different colors on the surface, but I think this won't affect you if you invest in a rather pricey, high quality mouse pad such as this one.
I would personally use this mouse pad, and I've found it to have the perfect surface for me—it's a pity I don't like the size options. I would definitely recommend the MM350 series to anyone who finds its specifications appealing. It's truly a masterpiece of a mouse pad, and that can be seen in the price tag as well. At $24.99 for the large and $39.99 for the extended version it's relatively expensive, but so is the competition—I would still call the MM350 a fair deal for what it provides, especially if you're looking for maximum comfort and performance with your gear.