I only have a few Boden pieces but they have held up really well and I've been happy with the quality/fit. I still have a hard time paying full price for their items though. I usually wait until what I want is on sale.
I wear a size 8 pant/shorts and a M in tops from Loft and my tops from Boden are also a size 8 (I don't have any bottoms from there) so I'm not sure about the vanity sizing stuff.
Eep. I just ordered two dresses and a top because they had a pretty good promo going on. I hope they fit. If they're nice enough quality I'll probably swing to have them altered if necessary. I hate buying clothes sight unseen, though.
I think the quality is great. But one of the things I like best is their GARMENT sizing charts (not a standard sizing chart - it varies piece by piece.) Some of their stuff does run big I think, but you can consult the chart and choose the best size for you. It's been very accurate for me when I order from there.