There is an interesting piece by Cyrus Sanati on the Lenovo (previously IBM) Thinkpad.
In my opinion, Lenovo already damaged the Thinkpad reputation. It’s build quality dropped almost immediately. The T43 wasn’t nearly as well built as the extremely T42. The T42 was a work of art with properly fitting everything. My T43 had been reliable, it still works, however it was never of the same quality as the T42 or A31. The plastic never perfectly aligned, slight gap between the optical media bay, the optical media drive tray flexes way more than it should. The T50 series was even worse and flexed despite “improvements”. Small things, but they matter.
The reason why Thinkpads still have a reputation is because they have no real competition. Apple has top notch build quality, but it’s not a PC. Sony is the nearest competitor, and it’s not really in the enterprise space, and isn’t quite up to par with the Thinkpad still. The Thinkpad wins just by beating it’s notably poor competition.
If someone figures out how to reproduce Apple’s build quality, Lenovo is in deep trouble. Until then, they will continue to do just fine. If Lenovo wants to protect itself, they should start competing with Apple in terms of quality, not aesthetics or consumer features.