I like it when the arrow keys are about as big as all of the other buttons. I find it very uncomfortable to use the extra-thin keys, particularly when playing games (which, thanks to Emacs, is where I use arrow keys most of all).

The arrow keys are tiny. Half-height makes the rest of the keyboard look nicely symmetrical but it makes people suspicious.

FWIW, I use Thinkpads as my personal laptops and I find the half-height arrow keys on my Apple wireless keyboard fine, but mileage may vary.