They just feel great to type on. It's probably a combination of key travel, getting the scissor mechanism right, perfect force needed and the feel of the depressing and popping back up of the keys.

The current gen is oookay to type on after you get used to it, but when I go back to my X220, the difference is that the X220 is a _joy_ to type on, rather than just okay. They also seem to last pretty well, given how old that X220 is now.

The 7 rows were nice because you had a few extra "media" keys without needing to Fn-combine (assuming you've set Fn to be off by default so you can use the function keys for your software).