Yeah, honestly. Kaguya's fight in highly misunderstood. The only attack I agree will occasionally BS wall you is her second non-spell. I've fought this fight over 50 times (nowhere near my 250+ fights against Remilia >.>), and I understand most of her attacks.
Her opener has a far less tendency to wall you than Sakuya's opener. It is very rare that you are ever walled off with no prior chance to escape, and I find attacks that force you to quickly find an opening before it's closed off to be fun.
Brilliant Dragon Bullet isn't BS and anyone who says so is just butthurt at its difficulty. While I'd prefer the lasers to give you a bit more time to react, the card is pretty much just bullet reading while dodging high speed lasers.
As people have said, her second non-spell occasionally BS walls you, but let's face it: Most final bosses have at least one attack that can BS wall you. If nothing else, one Reimu death bomb completely ruins the attack by destroying the familiars.
Buddhist Diamond is just claustophobic dodging. I can't say it's the fairest attack in Touhou, but even when you're caught in a vertical shaft, the lasers have a smaller hitbox than you'd think.
Nothing wrong with her third non-spell, really.
Salamander Shield is the only spell card I dislike in this fight. It's just mostly simple streaming most of the time, but switching directions is really annoying. The fact that most people call this her easiest spell card makes me feel like I'm missing some trivial timing thing, which if it's the case, proves further that her fight is perfectly okay.
Her fourth non-spell is pretty easy, but in terms of atmosphere it's the best part of the fight. I always try to time the fight (not in an actual run of course) to have the climax of the song before the loop occur within a few seconds of the attack starting...my pathetic and cheesy love of how the music synchs with the battle aside, there's nothing wrong with this easy non-spell.
Life Spring Infinity...people need to stop >:U ing this spell card. Like Azinth and Baity say, it's always possible to survive. I'm not sure exactly how to manipulate Kaguya's movements, but even without that I die to this attack all the time because I suck at reading the lasers and the stars, as well as getting through the stars safely, and not because Kaguya traps me. Honestly, blaming Kaguya by being in the way of the red bullets is like blaming Suwako for you going the wrong direction in Party Start.
...WTF is with the Hourai Jewel hate? Seriously, what? I don't get it. Do you not like how a final spell card is micromemorizable? Do you not know the timing to change directions safely? Do you dislike the tight dodging you get late in the attack (if you use the same rhythm as me)? What? It's true I used to revile this attack, but it was because back then my computer was in slowdown hell, back when my computer dipped to 20 FPS for a quarter of a second at random intervals, making timing impossible. These days I don't have many gripes with Hourai Jewel beyond its nonexistent margin of error, and even then, it's a final spell card, it's SUPPOSED to be hard.
As for the last spells, I never take those into account with difficulty of a boss fight because they're bonus attacks. As long as I don't completely fuck them all up and make it to Rising World (if I don't, I don't get the epic explosion tm) I'm happy, though I'll say Rising World is either low tier hardest spell card in the series or just below hardest spell card in the series tier.
tl;dr: Stop bullying Kaguya. >:(
In other news, isn't it ironic? Most people talk about Kaguya being the weakest final boss in the series. On higher levels of play we're arguing about her being the hardest in terms of a no bombs run. :P
