I've used it on T410, T420, T450, T530, T61, T23.
You do have to set up acceleration and speed to suit you (takes a while I assume), and set them up differently than you would for a mouse.
I will absolutely agree that learning curve is higher for trackpoint and that it's less intuitive than touchpad - but it's a bit like Vi/Emacs vs MS Notepad - one is immediately intuitive, the other rewards you for initial investment. I think giving a random person a touchpad and a trackpoint, and asking them to immediately do something, touchpad will win. But I also firmly believe the achievable ceiling is higher on trackpoint.
I cannot imagine using it with my thumb!!
Interestingly, while I'm right handed and use my mouse with my right hand, I use my trackpoint with left index finger, thumb over buttons... but I think that's a quirk of mine and not a generalized thing.
Are there any models (of any brand) with a particular good touchpoint feel?
Edit: http://www.laptopmag.com/articles/looking-for-nub-best-and-w... Apparently, the Lenovo one is supposed to be good. Bummer, I don't like it at all. It seems to switch from moving slowly to moving really fast at a rather unpredictable spot, which makes it hard to make precise movements in a fast way. You usually overshoot about two times if you're trying to click in a small area.
Edit: LOL, it also only just occured to me that using the trackpoint with your index finger is the best option (I was using my thumb before). Work a tiny bit better (still not very well honestly).