I was just reading the detailed system spec in Dell's support website (notebookchat.com does not allow me to paste the link here, saying no links allowed in the message for users with low post counts!)
Here are some issues that I have found with this model:
notebookchat.com: Please confirm these in your review for the product. Thanks.
1- Camera is located at the bottom of the display. I don't know if this causes the face to look weird in the conference calls.
2- This is really sad. The top of the line Quadro video card outputs only up to 920x1200 in PC Mode, and 1920x1080 in TV mode, (1080p). This means apparently you cannot attach a 4K monitor directly to the laptop. Really, Dell?!! >:( :-\
3- The fact that you have to go with the 3 cell battery (56 WHr) if you want to get the second hard drive. Because of the placement of the battery and the hard drive. Take a look at the inside configuration of the laptop here: (Again the website doen's allow me to paste the link, but find it in the Dell support website.)
4- UHD power consumption is more than twice the FHD (9.23W vs 4.22W). Assuming you want to get the configuration with two hard drives that you can only go with the 3 cell battery, I don't think this would provide long working hours.
5- Camera's still image resolution is less than 1 mega pixels (0.92).
6- Something you wouldn't find by your own: battery has only 300 discharge/recharge cycles.
7- I searched a lot, but wasn't able to find the location of the microphone, as one of the previous reviews mentioned 5520 had its mic next to the touch pad causing very high noise when using it during a call.