Samsung seem to be have been focusing most of its time and energy on other markets away from laptops recently - most notably with smartphones, so while Samsung isn't a market leader in laptops, it's not a brand that should be dismissed either and a used Samsung laptop can make a good choice.
Samsung is strong with its tech support - always good to know. They provide good online and phone support should you ever need it. Samsung laptops are constructed well and are good quality, but they offer a fairly limited range of models - especially when compared with some other manufacturers. But if it's a premium Ultrabook that you are after or a pretty affordable Chromebook, that's when Samsung comes into the equation.