Also picked one up, here in the UK

Was very tempted to grab the 13" MB, but decided I would only regret the difference in graphics power later on as well as possibly FW, etc. Feels very big after my 12", but compared to some of the chunky PC laptops I've seen it's nothing.
Main concern of course being the screen. As it is with Apple, all is forgiven the moment you set eyes on how gorgeous it is. But from a more practical point of view - sure, you wouldn't want to have the sun shining directly on it. However so far in its most common location (my bedroom) I haven't noticed any reflections unless looking for them, and even then only in the darkest areas of the screen. I can live with it no problem after all, and must admit the colour vibrance is pretty sweet.
The trackpad is incredibly "glidy" - I'd place it as some sort of cross between the old trackpads and the iPhone. The iPhone is a basic 'glass', where your finger meets a certain amount of friction, whilst this has very little friction in comparison but has the perfectly smooth feel of the glass surface. The lack of friction does make it a joy to use for the multiple finger gestures etc.
Clicking is very solid. You certainly won't click it by accident. As mentioned, it's more difficult to click towards the top, kind of favouring people's habit of clicking towards the bottom. Main problems I have are trying to click the solid metal below the touchpad, and my unconscious habit of holding one finger on the 'button' ready to click it (at which point it tries to zoom or whatever). Should soon get used to it though.
Amusingly, the screen is FAR better than the one on my iMac - if there's any fading towards the bottom, I can't seem to notice it.
As expected, the build quality seems amazing. It's solid as, well, a brick.
Utterly love the backlit keyboard. The black seems to be easily attracted to my finger prints, but the lighting is wonderful and I already loved the chiclet keyboards.