I'm not the OP here but I am a thinkpad guy so I thought I'd offer my $.02. I recently upgraded from a very much battle-worn R32 to a new T510. The former was a value series but indisputably an IBM thinkpad. The latter is a Lenovo from the regular line-up. I've owned both since new, the latter of which I ordered custom-built.
What's your opinion of the new keyboards
I think the new keyboard is still great, easily better than any other on the market for a laptop. Response is great, a nice tactile feel. Keys are 95% size IIRC and no problem to type on. I type quite a bit - just finished my PhD thesis - so I probably know my keyboards better than most. I do have a couple IBM M series full-size keyboards (with trackpoint, of course) that I use for heavy-duty typing but there are times when a silent keyboard is called for and the T510 is great for that time.
My only complaint on the keyboard is that the finish leaves something to be desired. I have naturally oily skin which seems to eat the finish off fairly quick. My left mouse button, for example, looks quite a bit older than it actually is. I do keep a silicone skin on my keyboard most of the time, FWIW.
If so, any opinions as to changes in quality, keyboard or otherwise?
All in all, I would say my T510 is still a great unit. Hardware wise my only gripe is that this particular model (or any T510) doesn't have the ultrabay, and hence is limited to the system battery (though I do have the 9 cell). I can also tell you I have dropped my thinkpad from table height - while running - more than once already and that has caused absolutely no noticeable damage whatsoever to any part of the system.