I originally tried Mint 18 KDE on my HP laptop. The plaque on the back says it is a 355 G2 if that makes any difference. I was underwhelmed with the beta. It had a vicious lock screen bug. If you required your password for the lock screen, you were toast. There are various discussions about hacks and work arounds, but none of them seem to work on the laptop.
About a week ago I pulled down the released version and installed it on my HP 8100 Elite small form factor desktop, replacing Ubuntu 16.04 because it was sloooow and Unity really blows as a desktop. I was impressed that the first time the screen saver came up it showed a message saying the screen locker was broken and you needed to do the following:
login with password
then <Ctrl><Alt><F9> to get back to the windowing environment.
I was so impressed by this I did a fresh install on my HP laptop. No love! Never saw that screen saver message and cannot use the <Ctrl><Alt><F2> hack around. Probably has something to do with the blue <Fn> not being operational when the lock screen is up, but I do not know. I do know that it is a hard power down fix at that point so you have to set your screen locker to the maximum value. There does not appear to be a method of disabling the screen locker. I guess one could try to find the system setting which changes “Require password to unlock” false, but then you have an even larger security problem.
The default settings for KMail are completely unusable. Between the font, theme and color scheme chosen you cannot read your message list. There is yet another nasty bug in KMail, you cannot change the size of the font in the message list. Oh, to be sure there is a setting for it and you can actually change the font itself, but not the size. If you change the size of the ICON the entry in the list will get a bit taller making the font seem a little larger, but still unreadable for most. The light blue on white is a bit tough on the eyes, but if you change the message list font to Liberation Mono you can at least make it bold so it is more readable.
One thing worthy of note. Ubuntu 16.04 64-bit with all updates applied was slooooooow on my desktop, especially when trying to surf the Web. The beta of Mint 18 KDE on the laptop could get to the same Web page much faster than the desktop both going through the same router at the same time. Everything seemed slow. This desktop is a quad core I7 with 16 Gig of RAM and a super fast hard drive not to mention a video card containing 384 CUDA cores. It ought to fly. With Mint 18 KDE installed it has become its snappy old self again.
Btw, trying to convert KDE to a green theme was a truly wretched idea. Thankfully it is only bits and pieces showing the ugly green.