IBM is playing catching up with the rest of Dell, HP, Toshiba, Sony, Asus, etc.. when it comes to widescreen notebooks. They are still expensive comparing to the rest of the other guys. Their components are still behind, for example, LCD resolution, GPU, USB and Firewire (they are stingy on those), No DVI, Audio, Optical Drive (give me a break only burning DVD at 2X and no DVD+RW and Dual-Layer support?) The only things they have better than others are, ruggedness, portability, battery life (with 15.4" series they claimed to be up to 6 hours. in reality only 4.5 to 5 hours at most. so that is same par with other 15.4" notebooks), and technical supports. With the Z series in 15.4", their notebook is at 6.6 pounds, same weight as others, but they do have the option for you to choose titanium cover, big deal. So if you like the built, ruggedness, and technical support, and willing to pay for the premium go with IBM Z notebook.
As far as for me, I would choose IBM in T and X series over other companies even if it means paying for premium. But with Z series, I'd rather go with others.