The only thing that bothered me was adaptive brightness (CABC) that was fixed in my case with an unofficial panel firmware at some risk to brick the device. Coil whine is perceptable only if I keep ear close to the keyboard. No other problems.

If there is someone from Dell here: please fix CABC! Unofficial patch proves that it can be done. It's especially important for linux devs who switch between dark terminal windows and browser: CABC increases backlight brightness if contents of screen are light, and decreases if it's dark. So, I switch from terminal to browser, brightness jump is already unpleasant as is, but then CABC kicks in, increases brightness and burns out eyes. Switch back to terminal -- too dark, difficult to see anything. How it's even supposed to work... Another unpleasant thing happens when CABC starts to adjust brighness back and forth while I edit code, it's highly annoing when it happens.

Edit: There were also a problems with Atheros WiFi, but new firmware from Atheros's github fixes them completely for me. Works stable since June 2017.