I spent over two months testing and trying various auction management software programs, both desktop and web-based, and the only one that's worked smoothly and offered every feature I desired (and then some) was Mpire. I've had a couple of questions and one problem, and my response from their tech support was quick, accurate and *friendly*. Every auction loaded perfectly on the first try, my auctions look great, and the interface is amazingly easy to use.
At times, the formatting of text on the listing templates was a bit frustrating, but no more so than a number of simplified web-page creation tools I've used. There could be a few more graphic-based templates, but I'd rather have the nuts and bolts work properly than have tons of bells and whistles over poor underlying functionality.
One suggestion I have for new users is to create multiple templates for a variety of picture formats. I found single image and thumbnail versions of what was otherwise the same template very helpful. Also, folders can't have apostrophes in the titles.
The hosting space for images is decent-sized, and the upload process worked flawlessly the first time. Linking the photos to the auction listing is simple and allows visual selection. Being able to categorize images into folders makes the process easier yet.
Yes, I'm a fan, and I'll stick with Mpire Builder as long as I'll have enough items going up on eBay to make the monthly flat fee a reasonable expense.