There used to be a fair bit of buzz around them a few years ago. I don't have any experiance with them, though if i was interested i would check reddit for first hand accounts. KustomPCS is their offical UK distributor.They don't seem to have a UK reseller anymore.
Prices seem competitive, but I don't know how they compare to global brands you can buy from many retailers in the UK. And if they break under warranty it might be cost prohibitive to return to Poland.