This has now changed hands as of February 2010 and is now an Amercian style bar/restaurant called Profile. I han't been for some time but it used to be a reliable place, so it is a shame to see it go.
My brief impressions of Spiga before its demise were as follows.
The serve superb Italian pizzas from a genuine wood-fired pizza oven, with a very light, thin base and excellent ingredients. The pasta dishes are also extremely good here – the menu varies so it is not easy to single out a particular dish. Salads benefit from very fresh leaves and ingredients. Service is not slick but is pleasant enough, and the atmosphere is very lively.