Currently working on learning Spring which I'm using with hibernate on a web based project. Why would I want to learn something like flex and are the benefits worth the added work. Also what is the learning curve for flex like?
Does your project need a rich client? If it does, Flex is one of the solutions you could consider.
I found Flex pretty easy to get to grips with. ActionScript is based on EMACSScript so doesn't really hold many surprises. Assuming you've got a reasonable grasp of the concepts behind web applications you should find it pretty straight forward.