I like SF in general, and my favourite authors in this genre are Greg Bear, Neil Stephenson, David Brin - what I would call modern, hard-SF. I also like the older, "Golden-Age" SF authors, especially Heinlein, Asimov, and Bradbury.
The "Hyperion" books do not really fit either category, but are (to me) a brilliant combination of the two. The depth of character development, the 'hardness' of the science, and the embedded literary references strongly suggest it belongs in the "modern" category, but as you get in to the story, you quickly see that this work has an adventuring, space-opera thing going on. Simmons has created a truely vast Universe in which to tell his stories - as wide and well-populated as Asimov's 'Foundation' or Herbert's 'Dune' (possibly moreso), combined with the rollicking adventuresomeness of a classic Heinlein story. But, he manages to do this without seeming derivitive or old-fashioned. And, at the same time, he brings in a lot of the elements which characterise modern SF - realistic portrayals of the complications of space travel, human adaptations to non-Earth environments, and especially, speculation about the nature of artificial intelligences.
He also has a strong talent for keeping the reader hooked - for example, teasing cliffhanger chapter endings are common. One thing I don't particularly like about his writing is that he tends to switch tenses - one character's story-line will be in past tense, and another in present tense. I found that a little bit jarring, but not a huge issue.
All in all, a really rewarding series of books, if you like SF. The rumour on the Internet is that the first two books are going to be made into a movie to be released next year, but I have a hard time believing that one movie will be able to tell that much story. Time will tell.
The books are:
Hyperion
Fall of Hyperion
Endymion
Rise of Endymion
by Dan Simmons
I finished the last book a couple of weeks ago, and really liked it. The second two aren't quite as good as the first two, but he does answer a lot of questions, and the revelations are worth the read, I think. I was really impressed with the way the whole thing was wrapped up; good stuff. There's a boring section in the middle of the 4th book (he could have used a stricter editor there), but it's worth the trouble to plow on through, IMHO.