I have the 60" version of the 2013 model of the M series 50" that is for sale. I paid full retail for mine when new. It has held up like a champ and I think the picture is good.
That being said - the SENSOR for the remote is horrible. What do I mean by this? You have to actively POINT the remote at the far left corner of the TV for it to register the stock remote or the harmony that I have.
I have adapted to this over time, but it is extremely annoying. To this day my wife and I both swear at the TV probably 2-3 times per week when the macro i have on the remote either a) fails to turn off the TV or b) fails to change the input because we didn’t point it DIRECTLY AT THE CORNER OF THE TV.
Plenty of kvetching here:
Other than what I can safely call the most temperamental remote sensor I’ve seen on any device - it’s a good TV. Up to you whether the frustration is worth it to ya.
EDITED - Mine was in fact the 2013 model and I don’t know if it was corrected on the 2014. The case looks identical, but perhaps they addressed the issue. YMMV