I think 'Koishikute' has been quite a hit and miss single with western fans
Some love it and some just think it's boring and forgettable, which is fine.
I hope the Japanese public love it, though. I originally thought it was as generic and boring as I personally find 'Ai Wo Tomenaide' (kuu's most boring ballad to me, sorry kuu D: ), but after another listen to the longer preview I turned to really like it, and the melody got stuck in my head. I really like the melody, and how it gets more epic after the first verse.
I thought the covers could have been more imaginative, though.