I have used stakecube for around 8 months now. As an exchange, it is quite easy to use, less complicated than others I have tried. The faucets are useful if you want to learn how to trade before sending your own coins in. I saved some up for a few months and then exchanged them all to TRBO which I am now increasing by staking. I have tried both deposit and withdrawal and both are very straightforward.
The lack of documentation is only a minor inconvenience, but an explanation of all the features of the site would be a good addition. But still it is easy enough to figure out if you have already used an exchange and are familiar with the concept of staking.
Overall it's a good site to use, and the fact that you can try it out without investing anything by using the faucets is a nice bonus for those who like to learn by doing.