Update: the battery in this machine started swelling/exploding at 1.25 years Strongly recommend not buying one!

So I've now had a Dell XPS 15 9550 as my primary driver for approximately 9 months. I covered the (painful) setup process a bit when I first got it, so I won't repeat most of that here. Suffice it to say that it was annoying getting the Windows 10 install working after the Linux setup, and in the end I've not booted to Windows since the initial setup.

This is the top-of-the-line version of the XPS with almost all options at maximum, discreet nVidia graphics, 16GB of RAM, etc. It was ~$3200 CDN, so this is by no means a cheap laptop.

Biggest issue with the laptop is that it has a really annoying coil whine. This *apparently* has been fixed in later hardware, but my early-2016 device (particularly the power brick) has an annoying whine that gets really loud if I get it anywhere near my main desk where my desktop sits, and is noticeable in any quiet room. Dell wants me to spend at least 45 minutes debugging this from Windows before they'll fix it, despite it being a known issue with their hardware. So for now I'm living with the whine despite it kind of driving me crazy in the middle of the night. Had I known about this before purchasing I almost certainly would NOT have purchased the laptop, this is very much a PITA and unacceptable for a laptop that costs north of $3000. The insistence that I spend close to an hour of my time to debug a known issue seriously calls into question any value I'd hoped to get from gettinng the "professional" class machine instead of the cheaper tier machines.

The keyboard is... sub-optimal for programming. Everything is great except that the keys you use all the time, page up, page down, home, end are all function-key operations... which results in 3-key chords for a hell of a lot of things you hit all the time. I wound up having to map my right control and alt keys to home/end just to be usable, but the page-up and page-down keys are still a PITA. The keyboard is a reasonable one otherwise, easy to type on, and you can set the function keys to be real function keys by default (originally they required Fn+Fn1 to get function keys).

When you push the laptop (e.g. using the discrete graphics chip to do neural networks) the fan kicks in and is rather loud. The fan's intake is also *under* the laptop between the non-skip feet, so you need to set it on something hard (not your lap) to give it air. I often have to prop the machine up when it's doing anything intensive so that the airflow is sufficient to keep the machine cool.

Battery life under Kubuntu is not wow-ing. I can get a few hours off-mains, but it's nowhere near "all day" working on even non-intensive tasks, let alone when you start doing neural networks.

Linux/Kubuntu is still not great at handling the Quad HD screen. Lots of software (e.g. Java utilities, GIMP) just doesn't scale nicely, so you wind up with unreadably small text in tiny windows. The default Linux consoles are also unusably small, enough that I often have to stick my face right into the laptop  just to see what's on-screen. Full-HD option (1080p) would actually be more practical under Linux.

The laptop is fast, which is a big part of why I wanted it. Even the GPU is okay-ish as a local testing ground for NNs, again, a big part of the reason for choosing the machine. The screen is nice, but far too glossy. The touch-screen is occasionally useful for doing work with the kids, but I would have preferred an option for matte non-touch. The SSD is speedy enough. 16GB of RAM is a good minimum, but honestly a 32 or 64GB machine would have been worth it but wasn't available when I did my purchase. Virtual machines are memory-hungry beasts. The machine is reasonable looking and the case is solid.

Basically, this is an okay-but-flawed laptop. At 1/2 the price it would be a solid choice (assuming the coil whine is fixed). Dell often has specials that reduce the price by a few hundred dollars, so you might be able to pick one up for far less than I paid. It is not, however, a stunningly good laptop, just a slightly-better-than-average one.

[Update] one major thing I neglected to mention in the hardware issues was that with the default 16.04 install the trackpad was somewhat pointless. It was jumping around quite a lot whenever you were trying to click-while-scrolling. Switching to libinput and doing some minor configuration did reduce that jumping to not-a-concern levels, but it really isn't usable out of the box.