Being 100% deaf in one ear and only having 80% in the other, this was a big issue with me before upgrading. Went to Best Buy yesterday and played with one for about 10 minutes before heading to the check out stand.
For me, the sound is about 35-40% louder, and at the same time, much clearer than the original Ipad I upgraded from.
As a side note, Best Buy Trade in Program was offering $225 for my Ipad 32G WiFi, and when I went through the checkout process, I actually got $260 for the trade-in. I was so happy that I added a new Apple TV to my order.