From reading the reviews, these things are basically tupperware with computer components in it. Do not buy.
I have a laptop based on W230SD and I'm very happy with it. It contains a proper i7, not the underpowered U model and also has a 3k screen, 2x mSATA slots and is easily upgradable in a 13.3" chassis.
Not may people realise just how underpowered the U processors are for any real CPU intensive work. 4xxxU i7 processors are on a par with 2xxxx mobile processors.
You sacrafice ultrabook thinness and some battery life, but the return is a very powerful, cheap, upgradable laptop.