Hi,
I'm in the process of building my first serious Flex application and have started out using Flex 3.4 even though 4.0 was available mainly due to the larger number of resources. But now I feel very comfortable with the Flex API's, is it worth upgrading to Flex 4?
What are the benefits? And can I expect much pain when porting my existing code base of only a few thousand lines of code?
Cheers,
Chris
its not worth you can check some comparison in Google... maybe some other they will improve some features making it more sensible of migrating.
Adobe has a useful article on upgrading from Flex 3 SDK to 4 as well as using the new IDE (Flash Builder) with the older SDKs (something which I have personally found useful as there are a couple of useful addons in the new Flash Builder).
http://www.adobe.com/devnet/flex/articles/flexbuilder3_to_flashbuilder4.html
As for whether it's "worth" upgrading depends very much on your project. Flex 4 offers a number of improvements, specifically in the presentation layer. Google for "flex 4 new features" and you'll find some Adobe posts which sum up the features nicely.