On a technical level, yeah - a lot of the stuff is pretty basic.
But... at the same time it's refined about it, and when it's not being creative it's still being fun to play. I definitely noticed myself moving and dodging spells in a lot of different ways this time instead of the same streaming/micrododging etc.
Totally agreeing with you.
It seems to me that some comments here are unnecessarily harsh to the game, when the game impressed me a lot.
I mean, not every spellcard in the game has to have sophisticated programming behind it to make it great, right? Spellcard is more about the theme and pattern afterall.
Also, just because a spell is made just out of bullets with simple motion doesn't mean it's easy to make. There's loads of parameters that one can change to have the spell behave so differently that it takes a whole different approach to capture it. Then there's the difficulty in balancing the difficulty of the spell.
Gimmicks are plentiful throughout the game so I don't see how the spells are not memorable. Stage 5's spells were pretty, midboss's spell was so cool.
Then, ZUN has made thousands of spellcards probably throughout these years, so it's seems pretty unfair to pick whatever spell has similarity with old ones and call it unoriginal, when it's just similar concepts with different presentation. (and I think presentation is very important too,
)
It's quite impossible to expect ZUN to come up with like 50 new danmaku concepts for a game every year.
It's like calling Nue a Flan copycat when they are totally different characters with vast difference in personality and background.
I really liked
Music-wise, I don't really like the style of the boss themes ZUN had, it's more boss-like, but makes it less awesome to listen outside of the game.

The stage themes are really amazing, I can't stop listening to stage 4 theme's intro. XD
ZUN's putting more thought into the plot of the games isn't he? The character profiles this time are so unusually long and detailed O_O. The plot had me so confused too D: . I still can't comprehend what happened with the TD crew in the past after reading the character profiles...
and ZUN probably missed bugs because he only had one year since GFW to produce TD? As seen from the past, ZUN will release a patch very soon to fix major bugs anyways.