I haven't seen the anime, nor did I expect a manga rendition of Shakespeare's Romen & Juliet, since there have been many similar themed stories which are interesting and unique in their own right.
However, the plot of this manga seemed extremely rushed. New characters appear and never become fully developed. Tybalt, for instance, had a significant story behind him which was glossed over and cheapened until he became the skulking black knight who appeared when it was convenient and said a few cryptic remarks.
The manga also made use of typical cheesy gimmicks like Juliet saving the girl who hates her and, while bleeding, smile gently down at her and ask if she's alright, thus changing her opinion of Juliet. Or Romeo's last words to his father- very cliché. All that has been done a million times before and in better ways. Because this manga is already "borrowing" some details from Shakespeare's Romeo & Juliet, it would make sense for it to strive to be more unique, to have something about it that stands out and is innovative. Instead, it becomes this mass of Western and Japanese stereotypes, which would be hilarious if this was a parody, but because it took itself so seriously, the manga just fell flat.
Finally, the ending seemed extremely out of sync with the main plot. Oh, let's introduce a baddy at the last minute! The manga dragged on, and was only memorable in being how painful it was to read.