I don't think it's fair to call the Zelda games "kiddie", but you do go into them expecting at least some level of accessibility. After all, these games have successfully sucked in many moms, dads, grandmas, grandpas, Robin Williamses, etc. that previously had no interest in games and presumably little ability to match.
It's no surprise, then, that a lot of people have quit Majora's Mask before giving it a fair shake -- it's the least accessible Zelda game I can think of. It opens up right from the beginning holding a timer over your head, and it also holds you hostage at the console with no way to save for a pretty long period when you first fire the game up. You really need at least a free hour the first time you sit down to the game, unless you're in an emulator using save states.
If you've got the patience and fortitude to bear with the rough introduction, however, you'll find that the game really front-loads the demandings bits. The quest begins with Link ambushed by a wooden imp wearing the titular Majora's Mask, which seems to grant him omnipotent powers. Link is turned into a Deku Scrub, and we also learn we've got a three-day time limit or the mopey imp will crash the Moon into the planet in a fit of pique. You need to turn Link back into a human before that three-day cycle is up, and then you need to bumble across a talking scarecrow who randomly appears in one of two locations and teaches you a song to slow down time and make the pace of the game manageable.
With those two things in place, the game's much-ballyhooed "time limit" is pretty trivial. When time is slowed down at the outset of each new cycle (which you should be in the habit of), you've got a solid three hours of real time to roam about before the Moon landing (on your head) forces you to reset. You get to keep your most important items between cycles, too -- it's pretty much just consumables like bombs, rupees and arrows that are flushed.
But while you hang onto your most important goodies, the world itself does not remain changed by your actions. Each cycle reset undoes every good deed you've done, even restoring the dungeons to their original state. Killing the bosses of the main dungeons nets you their remains, which persist between cycles (or the game would be too maddening to play), but the bosses themselves revive and all the chaos they were presiding over in their little corner of the map is also restored to its original state.
It's not frustrating once you intuit the pace the game wants you to take it at -- use a time cycle to do the quest that opens up an area's dungeon to you, use the next time cycle to actually take on the dungeon once you can transport yourself to its front door straight off. Take the odd time cycle here and there to just explore Termina and find the optional masks and heart pieces, of which there are staggeringly more than usual given the game only has four real dungeons.
I apologize to whoever I'm inadvertently stealing this thought from, as I saw it in another review or article some time ago and I can't remember where now. But I saw someone say once that Majora is the Zelda game for those that prefer exploring the overworld to doing the dungeons. The complexity of some of the quests to get optional masks or heart pieces replaces the usual complexity of the dungeon puzzles. The four main dungeons are actually pretty simple and straightforward by Zelda standards (no doubt due to the time limit), though there are a few remarkably PITA bosses along the way. I played through this game au natural on my friend's rare Gamecube version back in 2005 and did just fine, but admittedly I wouldn't have got it done before Halloween this time out without abusing save states! The way I was playing it for this review was not the way it was meant to be enjoyed, though -- it's an intricate interlocking masterwork meant to be slowly explored and last you a good long time, not to be bulldozed through. Fortunately I'd already had the proper experience 10 years ago.
The gameplay isn't flawless -- the Z-targeting continues to be a little flaky, and the camera isn't always your friend, and both of these things especially tend to be true during the most annoying boss battles. But they serve only as irritant at worst, never bad enough to actually sink the game. If you really want to pick nits, the game does recycle at least half its art assets from Ocarina, but I can't say that I really noticed or cared personally. It's arguably the best-looking game on the N64 regardless, putting the mandatory extra 4MB of RAM from the Expansion Pack to excellent use for graphical effects that most games on the console didn't have.
While Majora is inarguably the most "dark" of the series, that's a low bar to clear, and the tone very rarely differs significantly from the general lightheartedness of Ocarina. It is beautiful and haunting in its own way, though. It's also the most imaginative entry in the series (alongside Wind Waker, but this one was actually brought to completion).
I can only wonder if, in some alternate line of reality somewhere, Zelda developed along the lines of this game instead, with one contiguous Link wandering the world having strange adventures like this and growing as a person rather than just resetting the same story with nicer graphics on every new console. Ah well. At least in this timeline we managed to get this game somehow.
with Miyamoto, Aonuma and script writer Mitsuhiro Takano on the game's development