Dare Obasanjo and Shelley Powers have been blogging about whether or not AJAX has a future, and what are the candidates for something to displace it. Timely, as I've been looking at some of this stuff recently, trying to get myself to play a bit in the client space.
Dare notes the development process is "a mess". I'm actually ok with it; it's not so terrible to not have a completely integrated development environment to do ALL your work. Even with Eclipse as my primary development IDE, I still have to shell out to PhotoShop or The Gimp to edit images. And I like that most of the tools are replaceable. I can freely move between Eclipse, TextMate, BBEdit, whatever, to do my raw text editing.
Which led me to start looking at Flex.
This kind of suits me, and since I tend to be a bit of a contrarian anyway, suits me even better amongst my IBM colleagues :-)
Dare also bring up WPF/E, but I'm not going to give it a serious look until I hear they have some semblance of a story for Linux.
Now, back to the matter I started with: Flex or AJAX; will one win over the other? I doubt it; each has their place. Think about this: could you build a GMail with Flex? The answer is a relatively simple "no", I think, because there's a critical bit of functionality that Flex does not provide: being able to imbed rando HTML in your app. Flex seems a bit constrained here. However, since a lot of email comes over as HTML now adays, how on earth are you going to render it in your app? At best you'd need to do this as a hybrid app; part Flex, part HTML. Great (not). Exact same argument for Google Reader.
Another pain point is printing. The printing story for Flex is pretty low-level. Sometimes I just want to 'print the page', but it's not completely clear to me how well that would ever work out.
So I'll claim there are certain apps for which Flex is simply not appropriate. And there are other apps, for which Flex will be just fine.
For my own selfish purposes, I actually do want to play a bit more with the weird and wacky MDI-ish mini-windows in my browser page thing a bit more. That's me, I'm a geek. And Flex seems to have a better story there, for now.
And I need to start doing some homework on Apollo.