I'm 5'8" and I bought a size 8 in the olive green tank dress. I love sleek, well-constructed basics in interesting block colours, so this is perfect for me. The double layer is great - much less flimsy than most ruched bodycon garments that might look outwardly similar. I also bought the blue skirt for my aunt (size 14) and she loved it.
I love the tank dress - and the green is such a nice summer green. Fabric is beautiful quality and it shows off my best bits.