I think their excellent, with great prices and best of all, each game that does not come with the original case. Instead comes inside a plastic jewel case anyway, JJGames used to put most of their game in a paper sleeve but Lukie games actually puts all their video games inside a brand new jewel case, and all the disc based games came without any visible scratches and were vary clean to boot.
I personally thought the DKOldies was too pricey for me, but I got a great brawler N64 controller from them recently and at least it was what I expected, and as advertised, but most of their prices were way over the top at DKOldies
edit I just took a look at DkOldies and it looks like they dropped their prices