Comment by delecti
Just about any tool will require a bunch of work at some point in the scale. Some front-load that, and some make it easy to get started but then you hit a point where you need to peek under the covers. Personally I prefer the latter, though I'm sure there's a lot of Stockholm syndrome involved in how I feel about Spring. And Spring's popularity means you're probably not the only one to hit any given problem.
This is a rational attitude but my experience is that engineers do not get to "the latter" at their leasure. What typically happens is that peeking under the covers is forced on them along with a tight timeline.