My aunt has one and the picture looks 'foggy', I don't know how else to describe it. Maybe she had a bad set, but I'm more inclined to believe it's too cheap. Doesn't cost much more for the low end Hisense TVs.
I bought a small Medion LCD TV for the bedroom from an Aldi store many years ago and returned it straight away - the picture quality and colours were shocking. It's possible they may have improved in the years since of course, but I would make sure you at least check out their returns policy if you're buying blind like that. I was able to return a small LCD to a store for my refund, but I doubt you'll be able to do that easily with a 50" TV.
Richer Sounds have 50" Toshiba and Hisense TVs for only £50 more which still might not be great, but likely to be better than the Medion and you'll get a 6 year warranty too.