I'll mention my experience mainly with the mouthpiece;
Upon arrival, it was stuck in that it would submerge and rise but could not be lifted off to change the temperature.
Three days later, the mouthpiece suddenly came off and I was subsequently able to both push it back in and change the temperature setting, with full functionality.
However, when the mouthpiece was fully extended, the purple/green that you would expect would not show - the yellow/orange/red temp indicator would instead. I figured out that I'd have to hold the mouthpiece slightly in to compensate and connect the mechanism, which is a pain of course; when you're passing it around or just chilling on it and the piece is constantly having to be pushed in, is reheating and stopping to heat constantly, which drains battery, an overall misfortune.
I contacted Ploom and received replacement mouthpieces (again, excellent customers service on Plooms part.) These now work great. I have small caveat, which is that now when I press in the spring (slowly, gently, carefully, one click) it occasionally literally pops up and off. I have not had much time for trial and error with this new mouthpiece, but assume it to be a minor issue that will repair itself.
Either way the device, with the mouthpiece on, now works exactly as it should - superbly. I really like the metaphor someone used earlier in this thread, if I were having problems like this with a beautiful woman, I would smile through them and continued making sweet love to her as often as I so desired. The Pax; a similar device.
Ah, I should also mention two things - In regard to my earlier post, I apologize for the font. I copy pasted it and did not notice, and one thing I loath is when people write in different fonts/colors in their posts.
Finally, as far as cleaning (cleaning and mouthpiece I see as the two weakest points so far) I am a lazy college kid. While some here have claimed that they can go weeks of 4-6 times daily vaping without having to clean, I do not recommend this. When I was having all of my mouthpiece issues, I developed the habit of cleaning which is quick, simple, and efficient, and I feel certainly optimizes.