I have had great results with it every time.
There is one more thing I want to check, though. I remember when ADDT had a similar product, was the issues it had were that if the image name contained spaces in the file name, the resize failed. Of course, while spaces in the file name is complete no-no for web standards, as you know; we have no control over when we hand sites over to clients and what they might try to put on it.
So, I still need to test that scenario explicitly. As soon as I do that, I will report back if there are any issues.