I finished Hard Boiled last night.
All in all, the book really impressed me. I'm the type of person that can't read just one thing at a time - I get bored very easily, so I normally have 10-15 novels going simultaneously, and choose which to read at a given moment depending on my mood. So was not the case with Hard Boiled - I read it cover to cover in about five days.
I found Murakami's language and style incredibly captivating. I'm not familiar with any other modern Japanese literature, and so this was something very new to me.
The only minor upset I had was the ending - as was mentioned before, it was a little more melancholy than I would've expected, especially considering the direction in which the protagonist's thought was going for the last few End of the World chapters (also the last few Hard Boiled Wonderland chapters, come to think of it..). All things considered, however, any other ending would've been too cliché or too expected.
I'm looking forward to some great in-depth discussion of the book here.