Agreed. I recently got an X1 Carbon to replace my old X61s. While there's still something nice about the x61s's form factor (oh 4:3 screens, how I miss thee), the thinner, lighter x1c is incredible to me. It's sleek, light, and comfortable. It's also far more feature-full: the hard mute button with an indicator light is a lifesaver for me when turning the computer on when I don't know if it's muted or not (and need it to be); the fingerprint reader that's always-on so you can swipe your finger from full-off and it turns on and logs in automatically is a great time-saver (don't have to wait for it to turn on, then swipe, then wait for windows to login); backlit & chiclet keyboard, quick-charge, better battery management, etc. etc. Not to mention all the general laptop improvements (RAM/CPU/SSD/etc.). Overall, I think it's a huge improvement over old thinkpads.
Only thing I really don't like is how wide it is. I'd much much rather a 4:3 13" than a 16:9 14". I guess the integrated battery is a bit of a negative, but for my use, it's a good tradeoff for the thinner/lighter build. Ultimately though, it's all about the trackpoint (aka nub) for me. I simply cannot STAND touchpads for most control (though I like having the option now), so as long as thinkpad keeps making reasonably attractive thinkpads with trackpoint mice, I'll keep buying.
Though, I will say, the T431s's lack of trackpoint buttons would seriously irk me.