There’s a pretty good reason I categorize Angel as a soap-opera. Nobody really learns anything, nobody really changes. The only way to leave is to die, because otherwise it would imply going through the same cycle of characterization that is part of every characters make-up. The prime example for this is surely Angel, whose cycle goes like this: sad and emo to deeply, violently obsessed with something to remorseful and a bit clueless. The first time you see the cycle it may feel interesting, the second time it makes you yawn and then you only get annoyed.
Other characters on the show flip-flop mostly between two emotional states/phases of development and in general every serious character growth or development is undone via authorial dictate and rarely feels like a natural development. That the series still manages to entertain is mostly due to its content, because even a soap opera can be fun when it includes regular monster killing.
As for what went on in season three: Angel got a son, a vampire-hunter from the past turned up with the help of a demon, the son got kidnapped, Angel got angry at Wesley and nearly killed him and Cordelia became a higher being and left. Yeah, it was really fun, most of the time. But the need to inject drama always ended up making the show look more ridiculous, not deeper or better.