I think the answer was in how you held it. I held it very lightly with the tips of my fingers and so could throw it around with real speed and accuracy. I thought it's shape made it far more manoeuvrable. Because it had a chord I never had any problems with orientation either. I liked it's solidity too.
For a long time I assumed that the criticisms came from people who had either never used it (or had used it very briefly at a reseller's). I still believe this to a certain degree. There was a lot of irrational and ill-informed Apple bashing at the time and, to me, this was just one of the anti-Apple style-over-substance mantras.
I also dislike the current cordless one too - people I work with leave the mouse in all sorts of strange places and almost always I seem to start driving it upside down. And the lack of proper scroll wheel is infuriating when trying to scroll through a CT scan or MRI - using the fantastic DICOM/image viewer Osirix and trying to scroll 1 image either way is quite tricky.
Steve Jobs explained to me that it was ergonomically superior to mice on which you rest your entire hand. The ‘Apple USB mouse’ was meant to be used without putting your hand down at all. That way, you wouldn't put pressure on your wrist and you wouldn't hold your mouse in the same position for too long.
At the time, the iMac had been out for 5 months (the first Mac that came with the Apple USB mouse). So SJ had received plenty of responses about it already, and no doubt he knew what the press had written about it. To me, he said “They'll get used to it, this is a better mouse.” As we talked, I started to believe it, and by the end of our conversation, I was convinced that yes, this is revolutionary and necessary. (I was 18 years old at the time, I had recently moved to the US, and MacWorld Expo was the biggest event I had ever been.) A year later, Apple replaced the model with the more conventional ‘Apple Pro mouse’.