I did it for a couple of reasons, one being I had just purchased the 1G not knowing that a new one was about to be released ( I definitely would have waited )
The other thing is that I wasn't happy with the on-screen volume control slide-- it seemed at times it would "lock" into whatever position it was in and I had to play around with it to adjust the volume. So, the volume controls on the 2G was an up-tick for me. What's ironic is , the on-screen volume slide on my 2G works like a charm!
By the way, it fits into my 1G Belkin soft rubber case pretty good. I am contemplating carefully cutting a slot for the volume controls. May not need to, though.