The benefit of separate components is that you'll get better sound and more features, and it's easier to upgrade in the future. The Denon AVR-1909 is a good example of this, as we felt its sound quality was a cut above the norm, and on top of three HDMI inputs, it offers strong support for older analog video connections as well.
The downside, however, is that it's tough to set up and use, even for accomplished home theater veterans like ourselves. If you're willing to put up with its ease-of-use quirks, the AVR-1909 performs well, but those looking for a more straightforward experience should look elsewhere.
Read the full review of the Denon AVR-1909.