I recently upgraded Business::Shipping to facilitate UPS Online rate lookups through Interchange catalogs. The module was very easy to install and configure, and the few small bumps that I did run into were addressed very quickly and thoroughly by Dan Browning. In my opinion, he's done an excellent job with this module and his support is fast, friendly and invaluable. Thanks, Dan!
I've been using Business::Shipping for a couple of years on 1 particular web server, but I recently ran into a problem with new installations of the module on 2 new web servers. My tech support team couldn't figure out what the problem was, and after multiple re-installs, they told me to get outside help. Out of desperation I contacted Daniel Browning, the module's author, and was shocked to get an immediate response! Furthermore, over the course of 3 days, Daniel reviewed my test script code, studied the failure messages we were getting, and suggested changes to my code. Eventually, we resolved the installation problem - and we could not have done so without his help. Excellent module. Excellent support.
I was able to get it working, but it turned out I only needed the USPS online mode, and it was simpler to post XML directly to the post office site. If one's needs are simple, this can seem like a lot of module. Can't comment on the overall performance since I did not end up using it in production.
I did find the docs a little sparse. For instance, when you initially communicate with the USPS server, you're required to do so in a test mode. That's supported, which is good, but the switch doesn't seem to be documented outside the code itself, so it took me a while to find it.