My girlfriend recently bought one for her daily driver. We decided to go with Arch Linux to gain access to packages as they release, rather than wait for the next iteration of Ubuntu or Fedora to get updates.
Here are my pros and cons:
Pros:
1. The hardware is great; the developer edition favors more Linux-compatible hardware (obviously), and for us, it didn't require very much setup. Usually the default configuration will be enough. The touchpad, like the MacBook, has a glass surface and feels excellent.
2. Like the MacBook, it's very light. The screen looks great, and honestly on Linux I prefer 1080p.
3. Dell has a very reasonable warranty, and is very quick to respond. Example: You can install whatever Linux distribution you like, replace the SSD (so long as you don't ruin anything while you're there, of course).
Cons:
1. It's fragile. Unlike the Macbook, you have to be at least (more) careful with this thing. We ended up breaking the screen without much effort; I wager it was the fact that it was in a backpack that got dropped somewhat aggressively.
That being said, we also bought the $60 accident protection, and Dell sent out a technician from a local repair shop to fix it for us within that week. If the technician can't fix it, they will over-night you a shipping box and a FedEx label to send your laptop back in.
Just be careful with it; treat it like the $1000+ machine that it is.
2. No replacing the RAM. It's soldered onto the board. That's not a problem for me because I barely push ~4GB.
Conclusion: I use a MacBook now; my XPS 13 is actually coming in tomorrow and I'm very excited. I think it's a great machine and a great MacBook replacement, and has excellent Linux compatibility. Dell's customer support is great, just be careful with it; it's not an aluminum body or several layers of glass in front of the screen. Make sure to buy the one with the right amount of RAM so you don't regret it later. If you're worried about storage, there's a $150 500GB M.2 SSD on Amazon, buy the lowest storage version and upgrade it. Get the protection plan. It's cheap compared to the cost of buying a new device.