Personally, while I love every last bit of Hibiki, I think things do get a bit more interesting after the writer change. However, most of it is simply a result of having gotten to know and love the characters over the course of the first half of the series. Without that familiarity and care, I think things may have hit a little flat like they do in a show like Kabuto (where I can barely bring myself to give a damn).
I think the most significant change to the show post 30 is just in the opening/introductions to each episode, and the lack of closing credits. Like JFC said, the show itself doesn't change too much, and the writers do a very good job at keeping each of the characters close to home. I guess things just kinda "pick up" more, but thats about it.
And Hibiki has a really good ending too.