Tables is the spreadsheet component, and it's here that the use of Flash really dresses up documents nicely. I ran into problems immediately, however, because Adobe doesn't follow Excel's syntax for formulas. It took me ages to figure out how to sum a column, and I never did manage to sum a row. If you're a die-hard Excel expert, Tables' weird syntax is sure to be a nonstarter. (See Tables screen image.)
Presentations is where you'd expect Flash to really shine, and they do look nice, but they aren't jaw-dropping. One nice aspect is the ability to upload FLV video. Otherwise, Presentations functions pretty much like the presentation components of the HTML-based office suites I tested. (See Presentations screen image.)
And that's the problem I have with Adobe's suite overall: There's no killer feature that knocks the competition aside, nothing that really stops you in your tracks. So why Flash? Microsoft doesn't even require Silverlight for its Web Apps (though it's optional). It's true that the Flash plug-in is almost universal these days, but using it opens up additional security risks that might be unacceptable for some organizations.
Still, as demos of what Adobe's technology can do, these apps are certainly nifty. Sign up and give them a whirl if you want to see one possible future for Web-based apps; if you want to do serious work, however, I recommend you stick with one of the other, HTML-based options.