Older ThinkPads are really well constructed. Opening them up is nothing like most laptops, it's basically a (mostly) magnesium shell built around your motherboard and hard drive with the keyboard plopped on top and 2 heavy metal hinges attaching the display to the body. Nothing is just half hazardly sitting in there, it's all very tight and thought out (probably because they've been using roughly the same design for decades). ThinkPads are generally the computers you'll see in police cars (in America) as well as one of the most common for lab work. ThinkPads also have a history in outerspace, they were the first laptop to be used safely on the space shuttle

Unfortunately, The t420 is often considered the "beginning of the end" or "the last ibm ThinkPad". Although the t420 was made by Lenovo, it still stuck with most of the original design choices from the IBM ThinkPads. With the t430 Lenovo made some rather unnecessary changes, most notably the keyboard. The t440 is much of the same. Lenovo is gradually making the ThinkPad into just a slightly beefed up consumer laptop, which is a shame