I bought the lightest shade they had in stock, Extra Light, which is the right colour for me in the summer. A lighter shade, Alabaster, is also available, and I think that in winter that would suit me better. In addition, there are 5 darker shades.
The coverage is really sheer, as you would expect from a tinted moisturiser it simply evens out any redness and makes the skin appear a little smoother. If you usually use concealer, you will probably still find yourself wanting to use some in conjunction with the tinted moisturiser.
It comes in a regular and an oil-free formation, and even though I chose the regular one, it's not heavy or greasy, and hasn't broken me out at all.
This wasn't my very first tinted moisturiser: I used Benefit's You Rebel Lite (£24.50 for 50ml) which is a little lighter than Extra Light in colour for a year or so when I was 14. It didn't make my spots any worse but it was a little streaky and perhaps a touch too yellow for my skin. I definitely prefer the Bobbi Brown formula. I would like to try NARS Tinted Moisturiser which comes in 11 shades, two of which are lighter than Extra Light, but it is £28 for 30ml, and it's SPF30. I've heard good things about it though.
In short, though, I approve of this formula and I'll definitely keep using a tinted moisturiser. I have a feeling that when the signs of aging start appearing (hopefully not too soon) I'll be happy that I'm already using some kind of base makeup and don't need to make the conspicuous move from bare skin to foundation.