This from people trying the new Java 1.5 language changes...
And generics: "In a nutshell, I have this to say about Java generics: my code feels more robust, but it's harder to read."Too bad the language is not simple enough to accomodate change, especially backward compatible change. Agile languages win again.
Also an interview with one of the authors of Hibernate: "Well, we are a bit stuck. We can't use many of the new features, because Hibernate needs to stay source-level compatible with older JDKs. The annotations stuff is okay, because we can provide it as an add-on package.
Update: A question in the comments asks how this is different from Python. My answer is "not much different". Python is a mixed beast when it comes to extension. Here's why...
The big problem is that these changes occur at all.
In Lisp, the core language (e.g. Common Lisp or Scheme) does not have to change much. Change is facilitated by making syntax extension a part of the language. And the core is expressive enough to ward off the need to change.
Smalltalk does not have the same syntax extension, but again is simple, expressive, and mature so that the existing message sending paradigm can be used to define new forms of control.
I am not sure why Python is changing or needs to. But the core language is more limited than Lisp or Smalltalk in the sense that it is "C"-like and distinguishes significantly between function calls, operators, and control structures.
A more uniform language would not have as many of these backward-compatibility issues. This is the main issue I have with Python... it's syntax is OK, but not great for extension.