I took the old GRE a year ago and HATED it because the computer program they used was ridiculously old fashioned. For example, when you're writing your essays, the 'tab' button on the keyboard cannot even create a tab space on your screen. I also hated the fact that you couldn't see how many questions you've completed compared to the total number the test would be giving you, and the analogies and antonyms tested you on so many random vocabulary words there was no garauntee you could know the definitions of all the choices to even be able to answer an analogy question!
The new GRE uses a more technologically advanced program (or so it seems), and it allows you to look at the total number of questions in a section. You can even go back to answer previous questions if you still have time during your section. I say, along with the 50% offer, that it would be well worth taking the new GRE versus the old version.