It's like any framework: once you learn it's idioms, you can be insanely productive. Unlike other frameworks, enterprise Java is all about flexibility, so in Spring land, it's often in incredible easy to tune or replace lower level components like connection pools, etc.

As such, I'd describe it as a good combination of highly dynamic architecture with lots of manual control. Of course, all of this is enabled with copious amounts of magic, which is usually why people don't like Spring.