I wouldn't say they are hard to train, they are very intelligent tho and that in itself sometimes is a problem..I found with mine that repeating the same command over and over does not work...So I make it more of a game, change up the commands, how they have to be done to keep it interesting, then they do very well..Having said that, boxers are notorious for turning a deaf ear when they choose, that gets frustrating...Angel is very intelligent, but also hard headed and her & I have butted heads, once literally, on several occasions, so I had to alter the way I train to suit her..I think that is the key, you have to sometimes use a lot of different methods to keep them interested, which is challenging, but the rewards are worth it....