For me, the best controller ever. Beautifully weighted and ergonomic, with all buttons and sticks falling under your fingers and thumbs so naturally it feels instantly comfortable and familiar. After a while you could almost forget it's there, but for the satisfying heft of the thing.
Next, the look of it - gorgeous. The off-white controller is great but this goes one stage further. It's all sleek lines and curves...the PS3's wireless effort looks archaic in comparison. I almost feel like buying more to use simply as ornaments! Yes, I am getting a bit carried away now. Sorry.
I have experienced no difference in performance at all between this and a wired controller, but would recommend buying the Play and Charge kit to avoid battery failure at the most inconvenient time!