I've been very impressed with this this year. I planted a small specimen a couple of years back and, having come through the last few winters it is now 6ft tall and has begun to flower properly, and what a lovely thing it is! Light pea-green foliage and narrow racemes of violet and white pea flowers - all in all with a light and airy feel. A nice contrast I think with the more solid presence of other 'hardy exotics'.
I recommend shelter, but otherwise easy going. Deciduous.
3L pots ~ £8