The problem is that you must make every episode good enough and that's a hell of a job if you make more than 700 episodes. Next to that, all kind of things that could happen, happened already and that makes it a bit predictable and gets really boring by now.
But I can't only complain about it. They try with every episode to make it awesome and it is nice done how people get killed with an magnificent plan, which fails when Conan realized how it's done. Also, are most of the movies and specials much better, than the episodes.
In the end I've to say that it is worth it to see a lot episodes and the movies, but take the time for it. Other ways, it could really get bored
