I used ABP throughout my dissertation research, and I really enjoyed using it. It allowed for coding multiple observation methods simultaneously (i.e., scan and all-occurrence), and you could add multiple modifiers to further clarify your observations. Importantly, it exports each observation as a csv file for quick conversion into Excel, which saved me hundreds of hours of coding.
If you have specific questions, I'd be happy to answer them, but the app gets a big thumbs up in my book!