I've recently finished Martin Mystery and reviewed it, so I'd like to give you a little feedback:
I think that the game is above average. It makes very good first impression. I've been especially glad because there are so many objects player can interact with (which aren't neccesary to deal with any puzzle !), and there are objects which can be taken, but play only the role of "red herring". There are so many games full of beautifull but almost empty places, and few objects to find and collect. MM is different.
And there was really great idea to make a puzzle which has its solution inside the box! (unfortunately, here in Poland, we are offered a version without it)
But while playing I started to be angry because of pixel hunting. I really don't like it. And I had an impression that the main difficulty was, unfortunately, finding an object. The way it should be used (when found) was rather obvious most of the time. There are too few "creative" puzzle (like the one with photocopier for example).
I regret that Java character is rather underdeveloped almost needles and useless.
Bugs and English translation was also problematic but I'm sure you already know about it.