I have newly installed 42.1 with kde plasma 5 desktop installed on my Acer 5750.
Works well so far apart from the occasional freeze up where by the desktop becomes unresponsive. The cursor will not move, keyboard unresponsive unless there is a combination of keys I can try to get out of this? So far all I can do is pull the power and shutdown completely.
I was going for a possible video card issue. Looking on google, many in earlier versions of Plasma 5 reports random freezing with systems using Intel based graphics cards/drivers.
My laptop has the integrated (with cpu) Intel HD3000.