Pros:
Excellent Linux support, zero issues even on day 1
Performs very well
Good battery life (my fans never even turn on during normal use)
Inexpensive (mine was about $850, you can spend more if you want PCIe storage, or other high end upgrades)
Expandable (standard 2.5" SATA, upgradable RAM, upgradable WiFi)
Full port selection (2xUSB-A, 1xUSB-C, HDMI, Ethernet, SD Card, Headphone)
Good keyboard, TrackPoint mouse (touchpad is also a "precision" touchpad, though I dont use it)
The 1080p IPS screen is pretty good, and standard, unlike the last ThinkPad I had
Good BIOS update support, ThinkPads are supported for many years including very fast turn around on things like BIOS level security updates
Negatives:
The build quality could be better (its not a MacBook), but it feels solid and I've yet to break a ThinkPad. If plastic bothers you, look elsewhere.
Other computers fit a 13.3" display into the space Lenovo fits a 12.5"