Just bought C6 Quad 4G in a Black Friday sales in Poland. At ~110 US dollars I paid, this is an absolute steal!
Device build quality is great, matching phones of twice the C6's price. LTE works great, my top download speed so far being 101.3 Mbps! (network: Plus, Poland). The screen is decent, brightness is fair, I just wish it was qHD rather than FWVGA, as pixel density is rather low. Battery life is fair, it should last a full day of regular use, I guess.
My only disappointment is the device memory layout: while it is announced as 8 GB, there are two partitions, system one sized at 1 GB and the other one ~6 GB in size and apps can only be installed on the smaller one, which fills up pretty quick. It's not possible to move apps to the larger position, and that's so annoying!