On the plus side its a solid and stable dev machine, iterm seems slower than the linux terminal. Rubymine, pycharm etc are stable. Google cloud shell freezes in browser sometimes but firefox quantum and chromium work pretty well otherwise. It also works great with my uhd monitor even tho it doesn’t have a dedicated graphics card.
But, I encounter screen tearing a lot on web pages. The trackpad is horrible in comparison to a macbook pro. There is some pretty nice support for multiple workspaces but they dont have the amazingly useful trackpad gestures.
I honestly feel like if there was a thinkpad with a trackpad as good as a macbook pro 2012 then there would be no problem switching.
My X230 is buttery smooth. The X1 Extreme and T490 I've tried, not so much.
Build quality is solid and keyboard is great. Speakers sound pretty rough but get decently loud. I got maybe 7-8 hours of use with the screen at 60%, and alternating between coding in Emacs and watching some videos.
I've tried Manjaro and the latest Ubuntu 18.04 LTS and have had no issues that would be a deal breaker. The only annoyance is jittery movement with the TrackPoint, but I've had that on every modern ThinkPad running Linux. I've been leaning towards using the trackpad more often and it seems to work okay.