I guess MediaMarkt is OK, when buying something simple. The people working there are not really knowledgeable in their field though. If you need professional help, I would go elsewhere. Where the nightmare begins is if you have some issue with one of their products. MeidaMarkt would say that they are just reseller and they can forward your product to the original seller for e.g. repair service. However if the service did not fix the problem, there is anything else they will do for you and you end up with a faulty device. The people working in the customer service are also very rude and without a proper knowledge of consumer law, so they might give you wrong advises. All in all, if you have any other option, try not to go there.