To be honest, the only things are started to go downhill are her lyrics imo.
I love Ayu because she's not the usual pop-star, with cheesy and stupid lyrics. Her lyrics are pretty meaningful for a mainstream singer. But I find her lyrics the same lately.
She seems out of ideas. She don't know what to talk about else than 'yay we walk under this bright sky, together!' 'I hope this song reach youUuUuUu (this is a vibrato

)'.
Luckily, she has written some awesome lyrics lately ,especially before NL, but they're few :|
I agree with Strawbari btw, she's keep changin' musical style even though she's more pop-rock oriented. Anyway I keep follow her, because my love and respect for Ayu its not finished yet. And I'm hoping it won't never finish. She just needs some inspiration and write brilliant lyrics again

I trust in Ayu.
lol I hope to explain all of my thoughts clearly ;_; sorry if I made mistakes.