I've written about this before on HN, to the point where it's starting to feel a little rediculous, but my experience has been so positive I view this machine as the modern replacement of the glory days MBP. I have the 2018 edition of this laptop and to this day it performs amazingly well.
Battery life is on par with the new MBP I used for work in 2016. With Terminal, Chrome, Signal, PyCharm, and Hangouts open I consistently get up to 5 days of battery life. Suspend and sleep mode works perfectly when opening and closing the top. I do think TLP[1] is required for this though. If you upgrade Ubuntu from your stock installation from Dell, the config might be lost though.
It has literally never crashed on me. I've had absolutely no stability issues.
OS upgrades are seamless and have only resulted in performance improvements. I haven't noticed any issues from Intel microcode updates, but this is anecdotal and I haven't tested this thoroughly.
It's the closest I've gotten to a MBP in terms of mouse pad quality. Gnome on Wayland provides great mouse pad gesture support, but X Org definitely still works, though I permanently moved to Wayland over a year ago.
I can't comment on Dell support, because I've never actually had to contact them.
Happy to answer any questions anyone has.
[1] https://linrunner.de/en/tlp/docs/tlp-linux-advanced-power-ma...