I love "Castles..." the board game, and this app is a good proxy for it. The AI is pretty predictable, though, once you've played enough games. The AI players also make some very unusual choices at times, such as placing rooms illogically or passing on every turn simply because they have the 5-coin bonus card.
There are some rule bugs such as AI players on rare occasions closing off or blocking all of their open doorways, or being able to collect the corridor room completion bonus twice in one turn. The AI players also have a very annoying quirk of pricing very valuable rooms (i.e. king's favor bonuses) very low so the other AI players can buy them cheap, and somehow knowing which rooms are valuable for me (based on my secret bonus cards) and pricing them very high- almost seems like cheating at times. Don't get me wrong though, I do enjoy playing the app a lot, despite some annoying quirks.
Some things I'd like to see in a future update: a cleaner, tidier interface (it's hard to see the scores as they pop up, and avoid having parts of the interface cover large portions of the board); smarter, adjustable AI; INTERNET MULTIPLAYER; a digital rule book for new players (the tutorial isn't very helpful).