After playing through this game in about 8 hours, I have to say, that it was at last worth it. Although there were some difficulities which I personally could only leave behind me by looking at one of the good guides which gives away hints rather than the direct solution and which to some extend gave me new motivation to get into the game.
I did record all of my sessions as a Let's Play, so I wanted to finish this game anyways, otherwise I wouldn't have started it as a project.
To start with some pros, I liked the atmosphere in this game very much. The choice of sounds, music and voice actors was excellent considering this is some sort of Indie project.
On the negative side, the puzzles in the game were too difficult to grasp, too many times. The description wasn't always as clear as you might think. Even when considering this is still an exploration and adventure game, the puzzles could have been made better. One example might be the navigation puzzle at O'Sullivan's Bay.
Nonetheless, I do recommend this game to others, who like to explore a very dark, tragic and partially confusing story. It is very well written and does definitely fulfill it's point as a part of the game.
Second downside for me is the relatively bad performance and optimisation (probably only on lower-end). I understand, that a big part of the whole Island is being rendered at the same time but this game could have been made more frame friendly with comparable or better graphics in e.g. the Source Engine (see Dear Esther).
If you use an engine, know the details. Get the best out of it and don't just rely on the fact, that hardware is getting better everyday. But that is a debatable point.
Conclusively I want to state, that I really enjoyed playing Montague's Mount, especially in the tense moments leading to the end. Getting to know the story one bit at a time, finally completing in the tragic story it tells and getting to know the person and character you are playing.
Feeling empathy, or disgust? What went wrong, what went right? Decide by yourself.