tl;dr mileage depends, but it's universally accepted that Broadcom cards are shit.
Lazily poking the screen for browsing the web is a mobile paradigm that I welcome on the desktop.
The only thing that annoys me is not having a dedicated home, end, page up and page down buttons. They're mapped to the arrow keys + Fn.
Speaking of Thinkpads. My first is a T450 which I got for work recently. It's solidly built but lacks a premium feel to it. Also the display has awful viewing angles.
It's totally enough for everything I do: web, movies (OK, very high quality happens to be a problem), music, programming, photo/video editing and even games (Half Life 2, Civilization V and Oblivion are level expected to work very well on high details). I don't know how It would manage with full blown KDE/GNOME desktop though (I prefer terminal+tiling WM). If you don't mind small size (I love it) I recommend it. Really the only thing that doesn't work well is that for some reason shutdown works like reboot so you have to turn of using power button, but who cares If you usualy just swith to the sleep mode.
Best battery-time vs price ratio ever.
However, you'll have to learn to live with small disk space.
To find disk usage:
df -h
Also, this is useful to find large files: du -h . | grep "[0-9][0-9]M"
Since chromebooks have SSDs, these commands run faster than you would imagine.System76 also sounds great because they specialize in Ubuntu and I've worked on dell laptops before and love their build quality so it's going to be a tough choice :)
Here's hoping for a retro thinkpad next year. Until then, I'll hold onto my money or just invest in an ergodox keyboard.
Personally I still use a ThinkPad X220 and I would not consider the Dell's keyboard significantly worse (I prefer the key placement of the page up/down keys etc of the X220 though).
The only issue that I sometimes have with them is that they heat up really quick, so using them on your laps is a problem. It's not a problem for me, because, most of the times, I use them connected to an external monitor, keyboard and a mouse - it's pretty much on my table with its lid closed down.