Finally bought a Cubot X15 to replace my almost 4 year old GT99, I was originally waiting for EE to bring 4G to the area before upgrading, (but I would probably be a cobweb covered skeleton by the time that happened) and I came across one being sold as an unwanted gift, unopened on Ebay for £68 so it was too good a chance to miss.
I appreciate the risk of unreliability when buying from China, as I deal with them every day through work, however the GT99 has never missed a beat in over three years and has actually coped far better with being a full time home wifi hotspot, than a neighbours' branded phone which seems to constantly overheat when streaming via tethering for more than a few hours. Its ultimately the reliability of the GT99 which has kept me loyal to the Cubot brand this time around, and if it lasts for even half of the same period as the previous one, then for less than £70 i'd still be more than happy.
So far, so good the only negative i've found is that the SIm 2 slot is also shared by the TF card, so you can't use a second sim and a TF card at the same time unlike the GT99 which had a third slot, and this is a step backwards for Cubot in my opinion. But other than that, it works well and performs just fine and with 16GB ROM (just over 11GB when the System is taken into account) it will probably be quite a while before I miss the TF Card.