San Dimas certainly looks slick and has a few pleasing features:
* You can quickly flip between product description and seller feedback * Results and descriptions show a live countdown timer * You can set alerts for 10, 30, or 60 minutes before an auction ends * You can keep an off-line history of items viewed
It's a beta product, so I won't criticize the odd glitch and crash.
My probably with San Dimas is that I don't understand who or what it's for - beyond niche uses such as the off-line product information. The extra features are nice, but wouldn't it be better to build them into the web site or toolbar? Why would I want to learn a new tool when I am already familiar and confident with the web site which does the same thing?
As an exercise in programming with new technologies (Adobe's AIR) it's a great case study, but for a good user experience I'll stick with the site.