it ended with too many loose ends. It was interesting at the beginning but it went down hi...

I agree, though I still enjoyed it on some level

I can understand your disappointment, but I'll have to disagree. As much as I'd love for more, I still don't want it to continue. I think it ended on a great note, sure there's lots of possibilities but that's life. this story is somehow open and closed (depending on how its looked at). If you want a complete ending I'd recommend Fruits Basket, though in my opinion the ending felt incomplete like it was rushed to please the readers. I believe that this story's end is 'finished' and it's not lacking I felt a sense of closure. If I can finish a story where I don't worry about what happens next, I find that to be a satisfactory ending.

I'm not saying that the story didn't ended in a great note, it ended well for the main characters. But for me - and this is my honest opinion - I felt, while reading the manga and while the action was unfolding, that I was in a "pre-climax" point, where there were a lot of mysteries to solve and questions to answer, and then, in an instant, I was teletransported to the end and those mysteries and unanswered questions just disappeared in thin air.
Anyway, despite all this I enjoyed reading "Cubism Love".