The big drawback for me for the surface book would seem to be the subpar support for other OSs.
Pen support is better than the original surface pro's, which I believe were wacom. Hard to pin that on pen tech vs OS improvements, though. The pen needing a Quad-A battery is a bit annoying, but they're not too hard to find, and just one lasts a long time.
Battery life with a detached screen is short, but you'll only really need it detached if you're walking around with it. If you're sitting or lying down, you can just attach it backwards and fold it back onto the keyboard. Heavier, but not to the point of annoyance, and it gives it a nice tilt for reading things if it's on a desk.
Battery life with the keyboard attached is incredible, especially if you can dim the monitor a bit and run in battery saving mode. (The battery saver mode does have a pretty significant perf hit, though). Just don't try to use it at full speed, at least with an i7 and discrete GPU - I can kill my battery in under 2 hours if I try to run something like a graphics-intensive game. For dev stuff I've never had a problem.
Multi-OS support is probably an issue, though WSL does seem to do a pretty good job of most things.
It's probably my favorite work laptop to date. The only minor gripe is that I haven't been able to find a good combination of settings to prevent accidental touchpad activation while typing.
People also often mention coil whine which I haven't noticed on this model, the 15" might be different.
I don't know why you think Dell is "very low quality". I've seen Dell laptops last for years under heavy usage.