It’s a big issue right now as more sites seem to be embracing this visually rich yet unrewarding method of displaying their comics online. Zuda Comics, who DS has been following for a while now, employs this method for their reader and I believe I can speak for all of us when we say it’s an unnecessary trick to make people think something is better than it actually is.
Coffman brings up some very good points, so go read the entire article. He mentions the inability, at least thus far, to read Flash comics on iPhones, and the increased load times for sites using this functionality (or lack thereof). There are many other points, all valid, that must be considered when choosing how to present a comic work.
If you have a comic online or plan on posting one soon, do us a favor: 1) Peer review it first to make sure it’s decent, and 2) Read Coffman’s article on Flash comics and why they shouldn’t be allowed. Ever.