I generally find that abstraction is good, but layering is bad. Let's say I have components A, B, and C that all do something useful and are good abstractions, the difference between good code and bade code is how they interact. In bad code A will call B and B will call C, from the top level it's completely opaque how everything fits together. I'd much rather A returns something and let's the caller pass it to B. There is very little difference in code required but it makes a world of difference to making it comprehensible.