The keyboard is absolutely glorious, for one.
Sorry for the rant. I really want to love it, but I just can’t.
Quality also went down while with later models - back in 2014 I was laptop shopping, based on the X2xx series reputation I tested an X240 and it was crap, even the keyboard was super bad, I ended up getting a Dell xps13 whose keyboard was miles better and it still works today.
My daily driver (of sorts, don’t really need a laptop anymore) is a MacBook Pro Late 2013, with NixOS. It’s so much better in every regard, it’s not even funny. It also still has its original battery.