Sometimes I find them annoying and unnecessary, but it depends on the type of mini-game and whether it pops up right in the middle of the story! Some are genuinely tedious, while others are actually fun. So, I guess I'm kind of neutral about them? I don't know... I hold a "negative" opinion about them, yet at the same time, I also have a positive one.
Sometimes they're necessary to take a break from reading and process what's happened, but it's annoying having to play them just to progress in the story without the option to skip. It would be better if there were a skip option so the player could decide whether or not to play them! After all, it's a drag having to replay the same mini-games on every route just to advance the story >again<. It makes the whole experience exhausting and sooooo boring.