I have some Ebuyer branded ones, 85mbps. They have worked flawlessly for the past 3 years or so. I use them for connecting my TV to my PC to play movies etc and also for my sons xbox for online play. No speed problems with any of it. The only issue I had was when I changed my router to a Buffalo air station and it stopped them working, probably just a setting somewhere, but I then got upgraded by Virgin and the new super hub thing let them work again.
Best Cyber Monday deals 2015 live blog: Best UK Cyber Monday tech deals, sales, discounts & offers