Personally, I didn't enjoy this manga too much... yet I continued to read it.
The storyline is as original it's going to get for a common shoujo/supernatural manga, though at times I think it lacked depth and I was often confused about what was going on (but that might just be me...)

The heroine of the story, Misao, is your average teenage girl - apart from the fact that she can see 'monsters', who whilst yearning for a boyfriend, finds love in a man that isn't human.
She learns that he was her dear friend from the past and that he came back for her so that they could get married...

I don't want to spoil too much about what happens in case you end up reading it... but I found that from the very first chapter, the story was toooo quick to get started. I usually like it when a story doesn't take the first 5 or so chapters to actually get started, but with Black Bird I felt too many things were happening too soon and a lot of the plot is unravelled early... it just could have eased into the storyline a little better.

The characters themselves irritated me a little. Misao I wouldn't have minded if she wasn't constantly crying and blushing or having her whole life totally fixated on the man she's in love with (Kyo).
I also couldn't understand why she fell in love with Kyo in the first place. He's quite often harsh and abusive, and this doesn't just go for Kyo... throughout the manga Misao is being violated by few men and treated as an object. I'm totally against things like that so that let the story down quite a lot for me.

I don't mean to sound totally negative... I did get a little hooked at times, but I did get bored of the main couple sucking face on pretty much every page.
The art was alright and the story was okay... it just had a few letdowns. I would recommend it to those who don't mind total sappy-ness and can put up with all the sobbing and the sexist parts, but otherwise I wouldn't bother.