There's over 900 episodes, but only about half of them are actually relevant to Detective Conan's actual plot. Half of the show's episodes are filler, and can be skipped with zero consequences. The main plot episodes are all very amazing and well done; they're extremely dramatic and suspenseful leading you to actually worry about what will happen next. However, 'next' isn't always the next episode. 'Next' might be 5, 10, or even 20 episodes later.
If you want to get into the show, I recommend looking for the list of main story episodes. They're few and far between, but they're worth your time and effort.
The filler episodes themselves are also not terrible, but they all follow a basic structure. They also don't have much weight since they're not important to the plot; you know nothing's going to happen to a character or story development in a filler episode.
Last thing, the Detective Conan theme song, is amazing. But it has over 40 openings which heavily vary in quality. It's really hit or miss with the openings and endings.
