Quoted from the previous section "Flex originated as a program designed to help web programmers work with Adobe Flash in a simpler, more efficient manner." Meaning, for a web programmer/developer who is already familiar with web based applications, and coding languages, Adobe Flex would not be that difficult to use or learn. For someone with no web programming experience, Adobe Flex will have more of a learning curve to it. Luckily, Adobe provide several tutorials for customers who are trying to learn Flex. You can check them out at the Adobe Flex Developer Center.
One thing about all Adobe products, is that they have great integration with each other. They also have very similar user interfaces, in terms of toolbar locations, navigation, and features. So, if you have used other Adobe products (Photoshop), and find them easy to work with, Adobe Flex should not be much of a problem for you. On the other hand, if you don't like the user interface of programs like Photoshop, you probably won't like Flex either.