It is a joke answer because the song title is No Buts. Nothing fancy, just an uncomplicated elementary school level mention of butts joke.
Is Toaru worth watching... All I can say is it isn't my usual sort of jam. The series as a whole is a school show thing (the entire series takes place in a city that is nothing but schools and support services for those schools.) That's usually a hard no from me straight away. The Index series has definite harem elements, which counts against it. But it's kind of a mix of it either being harem, or just the shonen trope of all previous defeated bad guys eventually joining the good side (in this case with the females all crushing on the hero.) The slightly better spin-off Railgun is just a non-harem (or sapphic shojo reverse harem) retelling of some of Index's arcs from a different pov character. But it lacks lore from the larger series. And the spinoff Accelerator has really just started, and only has one season, but so far... so good. But it is the same story through the lens of a typical antihero storyline. But regardless of all the drawbacks, I do like the series. Throughout each, the music is pretty solid.
Is Index worth watching? Honestly, probably not. But it makes watching Railgun more satisfying because you know more about the world and the background lore. And that DOES make it worth watching. But ignore all the online watch order and timeline guidelines. Most are garbage and ruin the experience. Either go Index first, then Railgun, then Accelerator. Or watch in release order, which does keep the individual seasons of each show intact even if you swap shows between them.
