I got free passes from Peachpit last year, but I didn't bother this year. Unless a REALLY COOL new product is announced (which is possible) for you to go and try out, the exhibits only pass can only give you just so much entertainment. And it's a hassle to get to get there and expensive to pay for parking.
Just go on the first day that you can, so you can use said cool new product sooner than the rest of us. 🙂